Ol' Green '70 GMC C2500 Father/Son

[davem815]

We bought this truck back on Mar. 21 so I better get a project thread started before I get too far behind. Here's pictures (from the CL ad) since everyone loves pictures! (I can't figure out how to insert pictures here, then type below pic)
Truck: 1970 GMC C2500, Deluxe, 307 w/ 4 speed, gauges; no P/S no P/B. Canadian built truck. Seams to be all original except, seat, mirrors (non-original painted below eyeline in bed), and rims. Came with 2 split rim on the front and 2 16.5 steel rims on rear, plus the other 2 split rims and the other 2 16.5 in the bed.
Missing one hubcap, original seat, original sport mirrors, and misc. sheet metal from the rockers, floor, and cab corners. lol
Drove it home 1-1/2 hours without any issues.

[jfallon83]

Looks like it's in pretty good shape and good starting point. Good luck with your project and keep us updated.

[davem815]

We decided on this truck because to was a "runner and driver". Also, it was very original and not modifed. I knew I would need something that could be driven as we worked on it, to keep Connor's attention span. He 12 years old. We wanted to work on it together.
I was was looking for something with a lot less rust, but that's not easy to find in Indiana. So we found this, I decided in about 30 sec. that it was too rusty and didn't really inspect it. Connor cried when we left because he liked it, and my wife also liked it. We had looked at one earlier that was a lot nicer, but needed paint and a lot of work before it was drivable. He said "No" to it because "it would be too expensive and I would never let him drive it". I forget about it for a few days, then the owner texted and lowered his "bottom dollor" I knew if I went to look at it again, that I couldn't leave without it. The PO offered to drive it to me 1 1/2 hour so I knew he believed it would make it. So we decided on Ol' Green. Connor named it. It was cheap enough that 1) if I screwed it up I wouldn't be out much and 2) at worst case I could part it for what I have in it.
Here is Connor bolting in the seat at the PO house. I don't think I had even closed the deal yet. I had commented that " it wasn't safe because the seat was not bolted in" and Connor couldn't ride home in it. He took his tool kit and a pocket full of bolts to bolt the seat in. We drove it home together, an hour and a half, without any problems.

[davem815]

My history with these truck goes back to when they were new. My father bought a '71 in Nov. '74. I remember riding around as a family (2 parents and 3 kids) in the cab, vacationing in TN and camped out of a bed topper, dad getting the truck stuck in the mud more than once, and drift busting hood high drifts in the Blizzard of '78 (2 wheel drive).

I got to drive this truck occasionally after I got my license and remember the 3OTT and manual steering. The truck has been sitting since my father passed away in '87. My ultimate goal is to restore it, if it isn't in too bad of shape. We just added my name to the title and remove my fathers over Christmas break. I knew it would be too big of a project and take too long to get road worthy for my son, so we looked for something else.

We were looking for something different than my father's. (It a base model '71 Chevy C20 2wd LB, with 307 and 3OTT, no PS, no radio) Maybe a 4x4, or Highlander, or Sierra/Sierra Grande. So we got a '70 GMC C2500 307 with 4 sp manual. Almost the same truck! Except a , wife and son both liked the GMC grill better. It has definitely grown on me and I think I like it better than the Chevy's, although I'm still partial to the '71/'72 Chevy grill because of my dad's. Would have liked '71-'72 for front power disc brakes, but that will be a good upgrade project for Connor someday.

[68Gold/white]

I hope you don't find too many hidden rust spots, although you'll find them on pickups that have never been in the rust belt...
I like it! Looks like you made a good choice for a project. A great father/son time together in his teens deal. It's so difficult for youngsters growing up these days. Being at home w/ Dad, working together is a good thing!
Whatever his plans/ideas are will hopefully be something do-able, of course he will need to get a job and spend HIS money on it, to appreciate it.
It could be converted to a half ton, easily, those parts are all over.
Have fun!!!

[cooperhw]

Love the truck, but not as much as the Father/Son aspect of the project. Might as well figure to do whatever it takes to save it as I don't think you will have any luck prying that one out of your sons hands.
You see all the work, problems, time, money, or THE TRUCK AS IT IS.

Your son sees "The truck as it could be some day" driving down the country road, wind in hair, maybe girlfriend sitting next to him, radio playing, FREEDOM.

[davem815]

I'm trying to keep this thread up to date, but I just keep falling further and further behind. Lots of work being done on the truck. I will TRY to get this updated.

Just to be clear, this is our truck, not his truck. It will not be his daily driver, but will be a special occasion driver for the whole family.

We are currently buying parts and fixing mechanical issues to make it dependable and safe.

[davem815]

The first things we needed to address were some of the mechanical issues and drivability issues. There was a loud squeal while moving and the side windows rattling. The PO said the center bearing was bad. He was correct, but so was the center U joint bearing. I will write up the center bearing in a separate post.
We went to the Super Sunday swap meet in Indy and picked up several things we needed, window weather strip kit, heater lever kit, hinge repair kit, and son was concerned about the door lock knobs.

[Justin@EntropyRad]

Cool start!

[davem815]

Center Carrier Bearing

Did several search on here to review procedure for replacing the center carrier bearing. Great site and great write ups. I remember my Dad doing this in the side yard in the grass back when I was too little to care about helping. It is much better to have a concrete floor inside a shop to do this in.

Connor was big help under the truck, getting dirty, helping remove the complete drive shaft. We removed it all together, so that we could mark it and keep the orientation as originally balanced. Ours was actually easier than all of the search results I found because the slip joint is between the front and rear drive shafts. I didn’t have to remove a yoke, to get the center bearing off. It is a ¾ ton, leaf spring, with 4 speed granny gear.

My bearing puller was too short to reach the bearing, so I had to improvise. I attached the two set of arm to the jaws. I knew the bearing should be a light press, so I did not anticipate it being on too tight and I was correct. It came off easy.

I was concerned about pressing the new bearing on. I has read where guys used a piece of pipe and tapped it on. The pipe I could find that cleared the spline, was going to be too tight on the journal. So I used a properly size punch to tap the bearing on. I rotated from side to side to keep the bearing square. Only very light tapping was required and it was a very easy process. A second set of hands to hold the drive shaft was a big help.

[davem815]

more pictures

[davem815]

I posted SPID questions over on the main 67-72 message board to get more views. Questions mostly involved Canadian SPID differences.

http://67-72chevytrucks.com/vboard/s...d.php?t=669845

[davem815]

We also found the center U-joint was completely shot. This must have been where the squealing noise was coming from. First U-joint from NAPA was the wrong size, it was for a 3 speed. Installed the first cross of the 2nd U-joint, let Connor grease the needle bearings and installed the second cross. Could not get the cap pressed on all of the way. Decided something was wrong and took it completely out. I found one needle bearing laying on the bottom of the second cross's cap. We both blame each other, although I should have check it after he greased the needle bearings. 12 year olds don't have much patients to work slow! Got a third U-joint from NAPA, carefully installed it and reinstalled the drive shaft. Truck drives so much better now, without the driveline squeal.

We went to two junkyard on one day of his spring break. Picked up a bunch of misc. parts. Best parts may been shifter boot and floor mat.

I know the truck originally had base mirror because of the 3 pattern in the door. And I know the below eyeline mirror were not mounted in the correct factory locations. I found out the mirrors are different than the factory mirrors I purchased, so I guess we will stay with the mirrors we have and not drill another set of hole in the door.

[connorm]

I've been trying to update this thread for awhile but I was having troubles with my account. Anyways, I am davem815's son and have continued working on the truck and driving it.

I will update with the pictures and info that I have and try to bring the thread up to date. For now I will attach these two pictures from the weekend.

I volunteer at the National Auto and Truck Museum and the Early Ford V8 Foundation museums in Auburn Indiana and I was going to drive a 1948 Ford to a show back home. I go to college and wanted to make it to show about an hour away. I left with my girlfriend at 7 AM. Anyway the car was running really rough and was down on power so I decided to turn around and get it back. It made it within a mile and died and wasn't going to make it any further. So I left the car on the side of the road and ran back and got the GMC to pull it home. I grabbed a ratchet strap and a lifting strap to get it back.

After we towed the 48 off the side of the road we hit the road in the GMC. I filled up the truck right before we left and after 160 miles at 60-75 it used 5/8 of a tank. Not the greatest but it handled the highway a lot better than I expected and there were no hang ups on the entire trip. Not too bad for the back up plan.

[connorm]

I've been going through and looking for pictures but I don't have some of the early ones, I'll have to talk to my dad about those.

The mirrors that were in the last post got cleaned up and put on the truck. They're getting to the point where they need touched up. The farm bumper on the rear also got cleaned up but needs to be touched up, I actually took it off to do that but broke the bolts going into the bumper so I need to drill those out and tap them to get it back. But I'm getting ahead of my self there.

The front bumper is a better chrome bumper, don't look too close or you'll see its a Chevy that doesn't have the cut outs for the turn signals. The grille is a better one, if you look close you'll see that it's painted, it is actually a '69-'70 grille that someone painted, not a '71-'72 factory painted grille. The eye brows have been changed out a couple of times and I have better ones to put one but I have come to HATE that job. I don't know why it just drives me crazy. We also picked up the chrome GM front bumper guards and threw those on too.

Now to get to some mechanical, the brakes went out and davem815 redid all the brake lines on the truck. Those are the pictures that I couldn't find but I'll talk to my dad to see if he has any. It took way too long to bleed because we kept running it dry, I blame him and he blames me. I'm sure you're all familiar with that story.

We also picked up a seat for it, put a dash cover on it, I put a tach in, I cleaned the gas tank in, we had issues with it because we burned a fusible link up at the starter, cleaned up wires and checked all the lights. I'm sure I've forgotten stuff and most of this is just little stuff to make it a better driver.

Anyway I'll shut up and let you look at the pictures. I'll make a write up on the GMT800 rim swap, the '71-'72 crossmember swap and anything else I remember.

[hewittca]

Great truck and updates! It's awesome to see an old build thread resurface with current updates.

[connorm]

I'm going to try to update this thread in chronological order and not get too stuck in the weeds with all the nitty gritty details of what has been done in the past years.

First: Brake rebuild

For this all the lines were replaced. I was young enough I do not remember all of the specifics. We got a full kit but had to tweak the lines in several spots. If I am remembering correctly they were mostly the lines near the master cylinder. At this point the truck was manual brakes, drum front and rear. @davem815 could help with specifics and maybe pictures.

Second: Stud swap and GMT800 Rims

For this studs were swapped for the larger '71-72 studs, obviously new lug nuts were needed, then GMT800 rims and 285/75R16 BFGs were installed. To do this the recommended drill bit. (Off the top of my head I do not remember what size, 37/64" sounds right. If you need to know for sure let me know.) Then the studs were installed, shown in the picture I used washers, then I got an actual stud installer to use, no pictures of that. I did have a couple of issues I had were that Dorman did not send all of the correct studs. The threads that hold the rear hub on were cross threaded so that hub needed to be drilled with a hand drill and the studs had to be installed on the truck. And when installing the studs one of the lug nuts stripped out. When installing studs either use junk lug nuts or rotate between different lug nuts.

Part Numbers:

Front Studs: '71-72 Chevy/GMC C20/C30 SRW Studs - Dorman 610-181 9/16 - 18 Serrated Wheel Stud (Multiple different parts numbers will work here as the SRW and DRW should be the same but have different part numbers. The same with the C20 and C30 differences.)

Rear Studs: '71-72 Chevy/GMC C30 DRW Studs - Dorman 610-189.1 9/16 - 18 Serrated Wheel Stud (I am pretty sure these are the studs I went with, I know I went with the longer ones, these are 3 inches rather than 2 - 5/32 or 1 -7/8. This was so that I could run a 1/2" spacer on the rear so that the hub caps clear the rear floating hub.)

Lug Nuts: Conversion lug nuts were needed. This is so that the lug nuts will have the external thread for the hub caps. From what I read the GMT800's used metric lug nuts but there are conversion lug nuts available. I believe these are the ones I used: https://www.amazon.com/Nuts-Chevy-st.../dp/B009SDA6YA

[connorm]

There were some other maintenance items done, mainly a water pump and radiator hoses. Then after this a squealing started. This turned out to be a front driver's side wheel bearing. The logical solution is to do a crossmember swap.

During This the braking system was pretty much converted to '71-72 power brakes with front disk brakes. A full '71-72 front crossmember and master cylinder. Aftermarket calipers were used and rebuilt but they worked out in the long run. Getting brake hoses was actually a problem too, but my dad had a guy make up factory '71-72 hoses then we ground away the material not needed with the aftermarket calipers. New front brake lines were needed, but only fronts. Steering was also replaced, although the front crossmember came with outer tie rods, inner tie rods and sleeves were bought. A new used center link was also needed with the larger tie rods. Along with this there were a lot of little brake fittings and other random parts needed. This swap was not the easiest and there were many parts stores runs. I recommend having two floor jacks if you do this, or buddies, and not having a deadline as some figuring out and research is needed. I would say 99% of this was factory parts or just bolting and unbolting Lego style stuff, but there was "customization." The outer frame holes needed to be elongated for the bolts to fit. That took me embarrassingly long to figure out. Maybe I should have listened to my dad sooner.

Pic 1: One of dad and I's helpers. Dad in the background salvaging tailgate hardware.

Pic 2: Not a bad place to work. Dad's '71 in the background. Where the tailgate hardware was going.

Pic 3: About where I was finding out the holes didn't line up and thinking the old cross member had to go back in. Turns out they were really close. Some swaps don't need the holes elongated and some swaps do. Doesn't seem to be any rhyme or reason.

So, as I was going through pictures, apparently I need to track some more down. I guess I'll leave you on cliff hanger for this. Damn Google

[68bowtie]

Good progress

[hewittca]

I've been off the forum for a few weeks, so I'm just now catching up on your build. Nice progress and thanks for sharing the specifics! It's always helpful to find a thread like this when searching for info. Also, nice work on the wheel studs. For some reason, replacing studs is always a stress point for me. I can never seem to get them to full seat, stay tight, or go in straight.

[connorm]

Originally Posted by hewittca

I've been off the forum for a few weeks, so I'm just now catching up on your build. Nice progress and thanks for sharing the specifics! It's always helpful to find a thread like this when searching for info. Also, nice work on the wheel studs. For some reason, replacing studs is always a stress point for me. I can never seem to get them to full seat, stay tight, or go in straight.

I used a tool like this, I am at college right now and don't have it with me so I can't get the exact brand. The one that I had worked well and helped a lot. I did have an issue where I messed up the threads on one of the lug nuts because I did not have this tool at the beginning. I should have switched the lug nuts more often or something I guess. After I got the tool I had no problems.

https://www.amazon.com/Lisle-22800-W...SEALw_wcB&th=1

[connorm]

Well guys, I promise I'm still trying to be active. I still have to get pictures off of my old phone, but there aren't many left to bring us up to speed with the current state. I've mostly been driving it the last couple of years. Since my last update I have graduated college, gotten a new job, and moved. So I've been a little busy. I have finally found a spot to store and work on the truck near me, so it will be coming soon, and hopefully there is more progress. In the mean time I will share another build that I completed in the mean time.

I have volunteered at both the National Auto and Truck Museum and The Early Ford V8 Flathead Foundation Museums for quite some time now. Through this I have gotten to do The Great Race in the youth X-Cup class. What is unique about these museums is that the youth programs build the cars. Primarily this has been new aluminum radiators, disc brakes, electric fans, etc. Well this year we went a little more serious. I led the build and did a majority of the work.

This was a body off frame restomod(?). We rebuilt the engine, redid the brake system, rewired the car, and did some minor body work. Along with new body mounts and painting the frame. This took up quite a bit of time but it was worth it in the end. I have learned quite a bit from this build process and have quite a few ideas for things that I want to do on this build when I do it, but I'll get into that in a separate post.

Now enough talking, here are the pictures.

Pic 1. The 48 in the middle of the rebuild, of course showing off that flathead. It is a 49 59 AB that is bored .060, decked, 8 BA crank, and Red's headers. We, the youth, did the machine work and assembled the engine in Ohio at S-Tech Fabrications. This was an old school machine shop and the guy that helped us was 80+ years old and work as hard as us.

Pic 2. After the rebuild, waiting for my friend to bring me gas. Also fighting and ignition problem.

Pic 3. I drove the 48 home and went to a local car show. The 66 GMC is my mom's that she just sold. Gonna miss that truck. Nothing like a GMC V6 and three on the tree.

Pic 4. Ol' Green and the 48 on graduation day. At that point those were the only two vehicles I had at college. For some reason I stuck out on campus.

[connorm]

Next up, I did use the truck this weekend. I put about 200 miles on it, everything from highway at 65-75, to in town driving, and back roads 45-60. It took everything in stride. Although it did need topped off on some fluids and a new battery. Just old truck stuff.

I went to Ducktail Run but and all but got rained out. Ended up spending one night there but left to go to homecoming early. The truck handled everything well, can't complain about that with it coming out of storage.

What is coming next for the truck? I got a set of Ridetech shocks for the truck. They are actually old coilovers that I won't be running coils on, but oh well they were the right price. I want to focus on driveability mods for the most part. I got a factory filler for an auxiliary tank, and have been considering adding a Blazer/Suburban tank behind the axle. I also probably ought to get a new radiator in it. I'll probably go with a 4 core radiator that I'll get rebuilt.

Beyond that I would like an overdrive, but it kills me abandoning the SM465. I learned to drive manual with this truck with my old dog Spots, and those are memories that can't be replaced. I would like to add an overdrive unit like the Advanced Adapters Ranger box, but they quit making those in 2019. Those go in between the bellhousing and the transmission, which presents it's own set of problems. Something like a Brownie Box 5831-E is also an option. It's an auxilary 3 speed that would go between the transmission and carrier bearing. The E version has a 1.27:1 under drive, direct driver, and 0.73:1 overdrive. These should be easier to find as I believe they made more, but parts are getting somewhat scare. These are also larger and heavier. But I'm not necessarily going for the least amount of parasitic loss with an SM465 and Dana 60. I am already planning on replacing the Dana 60 with a 71-72 wider version, so when I do this I could go to 4.56 rear gears which would help with that deeper overdrive. That an swapping to a warmed over 400 sbc. would help.

You might say why not go with a Gear Vendors, and I probably should. I believe that if I could find either of the other option I should be able to do it cheaper, and possibly much cheaper. Also, having the twin sticks in a pick up would be really cool, and it's something different. I should probably just do a Gear Vendors and be done with it but oh well, I'll follow this rabbit hole.

Pic 1. My buddies 47 Hudson and my 70 GMC at Ducktail Run. Most of the Cars had left at this point.

Pic 2. Me and my buddy sleeping under my 70 GMC after the guys that had the tents that we were gonna use whimped out and took their tents with them. As you can see Banquet was involved, that along with Carhartts, insulated gloves, and moving your legs under the truck a 4 AM to get out of the rain worked pretty well.

Pic 3. My 70 at the tailgate. I was in a fraternity in college and tailgated with them. It turns out one of the alumni bought a 71 GMC new and used it to haul ~5-10 kegs to the house a week to sell. I'm in the process of tacking down pics now. I'll share them when I get in touch.

Pic 4. And finally visiting a local state park with my girlfriend before I left. This was at Pokagon in Angola, IN.

[clay68c10]

Man, that's awesome. You've got a lot of cool things going on. Congrats on your graduation and work.

Have you considered a NV4500? They're out there still and might be an affordable option. The new Tremec TR4050 truck box is cool, but I expect it's $$$

[connorm]

Originally Posted by clay68c10

Man, that's awesome. You've got a lot of cool things going on. Congrats on your graduation and work.

Have you considered a NV4500? They're out there still and might be an affordable option. The new Tremec TR4050 truck box is cool, but I expect it's $$$

I guess that I should have mentioned this option, too. I was about ready to buy one and was looking for awhile. I think that I've talked myself out of one for the time being. The Tremec TR4050 is another good option, along with the new TKX. I would have to look at price but they might be closer than you think by the time that you rebuild and everything.

At this point I would like to try to keep the SM465 and add some kind overdrive unit. If they still made the Ranger Overdrive that would make the decision much easier. Right now I am kinda stuck on the 5831E idea.

I am basing these off of the Spicer gear ration calculator, but these are very close to actual numbers.

Right now: 307 to SM465 (1:1 4th gear) to 4:10 ratio to WORN 295's on the rear end
2800 rpm is 67 MPH
3000 rpm is 72 MPH
3200 rpm is 77 MPH

I usually keep it between 65-70 MPH. This will net ~12.5 MPG. It drops significantly if I go over 3000 RPM.

If I go to a 307 to SM465 to 5831E to 4:10 ratio to WORN 295s

2800 RPM in 4 (SM465) to 5831E Low (1.23:1) is 54 MPH
I would mostly use this on highways that go from 60 to 45 and I could stay in 4th.

2800 RPM in 4 (SM465) to 5831E Direct (1) is 67 MPH
This will be the same as now.

2200 RPM in 4 (SM465) to 5831E High (0.73:1) is 72 MPH
This will be the same as now.

I am slightly worried about my 307 having the balls to pull 72 MPH at 2200 RPM. Or at least doing it more efficiently. I want to make it know that the main reason for this swap is NOT TO INCREASE MILEAGE. There are many more betters ways to increase mileage. This is to add a cool factor to the truck, and experiment a different way to get overdrive and keep the SM465. Any input from anyone that has tried this or heard of this?

There was also a 5831 that was offered that has a 0.85:1 overdrive that might be better. I'm also trying to keep in mind that I will more than likely being putting in a rebuilt engine in the next 5ish years, and a 400 sbc would be a very easy swap and would have more torque. I also need to replace the rear end, more than likely with another Dana 60 but we do have a spare Eaton HO52 to at home. But I could put 4.56's, this seems counter intuitive but could help over the splits with the SM465, along with the 0.73:1 overdrive of the 5831E.

Did anyone follow that? This is my brain barf of the day and what has been going on through the day. I did get shocks that I am going to throw on tomorrow because I will be home. Ridetech threaded body 3.6's and 6.9's. I will go into more detail about this later.