1972 GMC 2500 6.2 Diesel

[dagnabbitt]

I found this truck for sale online, it was listed as "72 Chevy", which I think is partly why it had not sold by the time I saw it (it was on for 14 days)... most people would search "1972"; "Chev"; "Chevrolet"; or "GMC", which is what the truck actually is. In Canada we have a buy and sell site called kijiji which is surprisingly cumbersome to use and only a maniac like me would search for 67-72 trucks using 99 separate search combinations just so I could see everything.

Anyway I found it, and I was immediately struck by how ugly it is, and just recently I was complaining about how the younger generation wanted to stick these godawful wheels on everything. But it looked very interesting, and I missed owning a diesel.

As I wrote in this thread I did end up making a trip to look at it, and I bought it. The driveability of the truck surprised me, it handles and shifts and stops like a somewhat modern truck and probably would do even better with more appropriate tires. The engine is supposedly recently rebuilt - I am going to research that with the shop that did it - and it has a tilt column that looks "factory". I have never had a 6.2 before, and I have to say: I like it. It is mated to a 700r4 trans and boy is it nice to drive on the highway with the low revs, my other trucks scream at 70 miles an hour. I have yet to fill the fuel tank so I cannot guess at mileage but it is pretty great.

When the money changed hands the young man who sold it to me looked a little distraught. He watched me load it and waited for me to drive away with it before he himself left where we met. I could tell he really loved the truck, and it was special to him. That's when I started to look at it a little differently. I now can see what he liked about the look of this truck, it certainly has character, and whoever built it really tried to do a good job: I could fool most people (not you, reading this, of course) that the diesel came with the truck in 1972.

As to the wheels and the overall paint scheme... on the way back home one kid almost ran me off the road leaning over his girlfriend with a thumbs up to make sure I knew he liked it.

I have written to the Canadian GM Heritage site for more info on the truck since the original emblems are removed and there is no SPID. The build sheet is on the way, should have it this week. In the meantime I am driving it and will soon get it on a hoist to take a closer look at it. For now, the wheels stay!

[dagnabbitt]

Been driving this all week on the previous owner's last tank of diesel, it sure gets great mileage. I spent about $30 at the car wash mostly to clean the engine bay, and vacuumed a lot of dog hair and cigarette butts out of the interior. Windexed the glass on the inside and fixed the jammed up seatbelts, it's quite a bit more enjoyable now.

Having got it on the hoist it seems to need a pinion seal, front brake shoes, and a front engine seal. Oil is... thin looking, I don't like the look of it. I bought a pail of Rotella 15/40, going to change the oil, oil filter - of course - and fuel filter. Rear chamber of master cylinder is low on brake fluid but no evidence of leaks, yet.

The box is barely held on the truck by three bolts, maybe. I expect I will do a little work to the box so there are more points for it to secure to the frame, the crossbraces are rusted out but I think I have something that will work. I have a rear dock bumper that I may put on, I think it will suit the truck more than the chrome sport one I have in my parts pile.

For the wheels, although I get a kick out of them because they are so inappropriate, I think they might have to go: they ride terribly and track all over the place, and I can probably sell them for enough money to get some extra parts for this project. Although I usually go for stock in terms of appearance I think that a diesel conversion can just pay homage to stock: I am thinking I will go with the below look that I have admired for a while, except I will go with a gloss black wheel instead of white.

[dagnabbitt]

I bought a dock bumper from someone locally a few months ago even before i bought this truck: I like these bumpers because they tell a story - corny, I know - and because they are absolutely original: no one is repopping something like this so it is automatically authentic. I really like the look of this one, it shows how a person's tastes change over time... I thought these things were the ugliest things going when I was younger and I would have left this one in a ditch without another thought back then.

I particularly appreciate these on a three quarter ton truck, I think it looks good one this one especially.

I call it a dock bumper because you can lay the tailgate all the way down and back right up to a dock with them, perhaps they go by another name. The corners protect your quarter panels quite nicely, and this bumper already had done so for the last truck it was on, it had been tweaked a bit on the passenger side. I gave it some bangs with a sledge to straighten it somewhat.

During the installation process I found that I would have to remove the hitch from below, so I did so. I will get some new grade 8 bolts and reinstall when I have access to a hoist and air tools again.

[dagnabbitt]

I realized I have not posted any interior pictures of the truck, and I really should because it is a treat. It's not totally my style but I am going to leave it alone for now... because elements of it really are my style. I do like the unpretentious gearhead aspects of a truck that looks like this and doesn't try to impress you.

The glovebox hides a pretty good sound system - just looked behind the seats and found an amp and a woofer I never knew were there - with NAV, as well as three switches: one for the heater fan (main switch is broken); one for a light "for rolling"; and one to fool the DVD player into thinking you are in park, apparently. The cab has a 60/40 bench out of an 88-89, along with shoulder harnesses which are honestly pretty nice to have since my wife will now ride in it. On the left side the builder frenched in the GLOWPLUG/WATER IN OIL reader which sure enough works well and I refer to it often, as well as a high idle switch. Under the ignition is the switch for the electric fans, which I discovered when I was stuck in traffic the other day.

According the the build sheet the tilt steering is not original to the truck, but it really appears to be an original tilt from one of these trucks. Engine and trans temp as well as a voltmeter have been added to where the original radio was.

Truck is really a blast to drive, I finally filled it up yesterday but I have been driving it everywhere.

[68Gold/white]

I wonder why the PO sold it??? Man, it has some things about it that are home made, but do work!!!
I like it!!!
I don't care for the wheels, but would likely leave them on, if tires are usable...not that big of a deal to me...

[dagnabbitt]

Originally Posted by 68Gold/white

I wonder why the PO sold it??? Man, it has some things about it that are home made, but do work!!!
I like it!!!
I don't care for the wheels, but would likely leave them on, if tires are usable...not that big of a deal to me...

I love the truck, I am driving it everywhere. I looked under the dash expecting to see a rats nest of wires and just found... really clean color coded wires with proper connectors. I am pretty impressed. A lot of this diesel conversion is very custom and I want to take my time understanding how they did it before I make any changes.

But: this week it is getting some attention mechanically, and I have a set of steelies that I hope to get powdercoated soon so those others can go... I kind of like them to be honest, but they just aren't me. I feel like I am going through a mid life crisis driving on them, haha. I figure I can get some good money for them and buy some new rubber though.

I am still hoping to make it my daily driver, more or less, during this winter. Need to do something about those cab corners though.

[68Gold/white]

I missed a chance to buy a one ton school bus. It was a 93 model, was not turbo'd, don't know if it was a 6.2 or a 6.5. Wanted to put it in my 67 C10, for a driver. Someone Waaay out bid me when the bus sold. Would have taken LOT of work, but would have been cool like yours IS!!!
Keep us updated! It will look very innocent with stock wheels. You will turn a lot of heads when folks hear that diesel...LOL

[dagnabbitt]

Originally Posted by 68Gold/white

I missed a chance to buy a one ton school bus. It was a 93 model, was not turbo'd, don't know if it was a 6.2 or a 6.5. Wanted to put it in my 67 C10, for a driver. Someone Waaay out bid me when the bus sold. Would have taken LOT of work, but would have been cool like yours IS!!!
Keep us updated! It will look very innocent with stock wheels. You will turn a lot of heads when folks hear that diesel...LOL

I found a guy to blast and powdercoat my steelies, I am hoping he can get the color I want, sometimes they just have the basics. But anything will be an improvement.

[dagnabbitt]

One of the previous owners was really keen on just being different. It took me a couple days of wondering why the sidemarker lights didn't look right before I gave them a closer look. They appear to be off a van, if I had to guess.

GM helpfully provides dates for all of these little parts and these read "1985". I guess I am going to have to find some stock replacements because I really do not like them. I understand that when on a budget you use what you have on hand, but that really cannot be the case here.

[dagnabbitt]

The guy I bought this truck from was certain that it was a body swap, ie that they just put a 72 body on top of a 1989 diesel chassis. I doubted that immensely - which is why I did not mention it earlier in this thread - having been under the truck I could see no evidence that the body and chassis were not meant for each other. There were no bolt holes that didn't belong and no others that seemed added. There were no weird body shims, everything lined up. I have a 1959 Apache on a 1997 Tahoe chassis so I know what to look for, I think. To add to my certainty, the bumper I put on last week literally needed just four bolts: the perfect holes were already there and it needed none of the adjustment that every other bumper install I have ever done had required. It fit like a glove.

I think that he just couldn't fathom any other way that the truck could have a diesel in it. But when ordering brake shoes and a pinion seals I did wonder for a moment. I needn't have worried, the 1972 shoes were the right ones. The rotors were in excellent condition and I left them alone.

The brake shoes were an easy install, sort of, except that when turning the wheel to get at everything I found that I am not crazy, the truck really does not turn right as well as it turns left. Turning left I can get 1 and 7/8 turns out of the wheel; turning right only 1 and 1/4. The tilt steering which I have figured out from the build sheet was not original was installed a bit hastily, the steering box is off center. I will be removing it and reinstalling that I guess.

As to the pinion seal there are a few different ones you can get for a 1972 2500: I ordered the one for the Dana 60, which is what I figured I had. When the box arrived it looked familiar. That's when I realized that I already had one: it was behind the seat in the truck, still in the box. Then when we got under the truck I noted that the u joint had been changed recently... why did they not put the pinion seal in at the same time? Looked like it had been leaking since the 90's. I got my answer when I tried to take off the nut (pinon nut?) and found I could not, even with a half inch socket and a snipe. Then a 3/4 inch impact wrench was used: the entire truck was shaking, dust and mud from 40 years ago was flying everywhere. Nothing, the nut not budge one bit. It was incredible. Finally my friend got out his torch and bbq'd it for a few minutes. At that point the 3/4 inch impact got it off. Clearly the PO had bought the seal, tried to remove the nut, could not manage to do it... and said the hell with it and threw it behind the seat. The diff was down a quart and since it only holds about two quarts, so quite a bit.

While I waited for the nut to cool off enough to reinstall I fixed a corroded wire for the interior light, that was pretty satisfying.

Next week is the crankcase or timing chain seal, this truck is making a mess of the street I park it on and I want to be able to put it in my driveway this winter. Also ordering rear parking brake cables, these are seized. At that point I will find out about the rear shoes and if I need a wheel cylinder, I am losing brake fluid from somewhere.

[dagnabbitt]

It's been awhile since I posted anything about this truck and the reason for that is that I have not gotten very far with it: this has been a really awful winter even by Alberta standards. Add to that the fact that a diesel doesn't like winter and I have to say that I have not driven it much.

The few times I have driven the truck have revealed that it has more or less no rear brakes. Check that: it has zero rear brakes. Wish I had video of it, but I discovered this when I got stuck on a sheet of ice. Yes, just a flat sheet of ice. The 6.2 weighs as much as a big block and I had no weight in the back. So I got stuck on a perfectly flat surface. I left it in drive and got out and watched the rear wheels going about 10 mph, then applied the brakes with my hand, and they kept going. Guess I will have to address that.

Weather hasn't stopped me from collecting parts, though. I have some stock looking fender emblems to put on it, some new (to me) seats and console, and an interesting trailer hitch that I think people will think is clever/stupid.

I also took a set of steel wheels in for sandblasting and powdercoating and ordered some conversion lugs and modern hub covers for it. I am really looking forward to driving this truck and working on it again.

In the meantime I also sent away for the build sheet for the truck, a rare perk of owning a Canadian truck. Aside from confirming that the tilt column is not original, it also lists a Z31 Advance Price List which I cannot find any info on.

[LT7A]

You may not believe me, but I really like this truck. I mean really, a lot. And I mostly favor originality in trucks this age. I think you tapped into the truth when you realized how much work went into it and how much the previous owner liked it. Even how the tan pieces in the interior all matched and were coordinated. I would even be happy keeping the OBS 60/40 seat. However, I cannot tell you how much distaste I have for the stripe-y rims. But honestly, if those were painted or powder coated a gunmetal gray? I think it would look really cool. They totally carry the stance off with that truck. I will follow your work on this avidly. I have completely lost my desire to ever have perfect trucks. And I have come to appreciate the character present in trucks like this one you found. It says a lot when a guy keeps saying how much he loves driving his recently acquired beat up old truck. And that he keeps driving past the gas stations.

[dagnabbitt]

Originally Posted by LT7A

You may not believe me, but I really like this truck. I mean really, a lot. And I mostly favor originality in trucks this age. I think you tapped into the truth when you realized how much work went into it and how much the previous owner liked it. Even how the tan pieces in the interior all matched and were coordinated. I would even be happy keeping the OBS 60/40 seat. However, I cannot tell you how much distaste I have for the stripe-y rims. But honestly, if those were painted or powder coated a gunmetal gray? I think it would look really cool. They totally carry the stance off with that truck. I will follow your work on this avidly. I have completely lost my desire to ever have perfect trucks. And I have come to appreciate the character present in trucks like this one you found. It says a lot when a guy keeps saying how much he loves driving his recently acquired beat up old truck. And that he keeps driving past the gas stations.

Honestly, that means a lot to me, because I wasn't sure too many would see what I see. Most people who appreciate these trucks lean towards originality - myself included - but this one seems to combine the spirit of 72 with a little bit of whatever you want. It makes me happy to think that people other than myself and the original owner would appreciate this truck: I love to drive this one.

On the subject of the wheels, the steelies I referenced above are blasted, powdercoated, and on the truck, along with new Firestones. It looks a lot better already, I am just waiting for the right set of hub caps and I will post pics.

This pic is from a couple week ago, ha. Did it start? Yes it did.

[dagnabbitt]

Well, I have my wheels back from the blaster. The finish I selected was satin black, which matches the black on the front of the truck.

These are 16" E250 wheels, and they are in fact the later version that are even more undesirable, generally, since the nubs for affixing hubcaps are absent. But that is fine for what I plan to do, which is put 2010 GMC hub covers on them. Should be here any day.

To accomplish this I have some "conversion" lug nuts that I bought on line from the Lug Nut King. These are 9/16", which are correct for 1972. For my 1968 C20 I have a set of 1/2" ones I may end up using if I cannot find the hubcaps I want. Check your studs before ordering, they made a lot of little changes from 67-72.

The tires are 235 85 16s, I am liking the tall skinny look and I expect that they will ride nicer than those 20s.

The jug of windshield washer fluid in the grill is functional, I replaced the squirter but I have no bottle, so there is just a hose going in through the top of it. I am looking for the auxiliary battery tray and wiper bottle combo that is sometimes on the forum but missed the last set for sale.

[68Gold/white]

Brothers has new Aux battery trays for sale. The used O.E. ones here, are usually priced about the same...

[dagnabbitt]

Mine has an aux tray, sort of. I am not sure if it is an OEM one, aftermarket, or homemade. I will have to remove the battery to see. It does not have a holddown clamp so there is a bungee cord in its place. I'm going to do a search and see if I can find a picture of what things are supposed to look like under the hood of a dual battery truck.

I suppose there is no need for a "correct" aux battery tray and wiper bottle setup in a truck like this. I need to reminder myself that this is an oddball project and that I need to save my money for more important things: like my lack of rear brakes.

[68Gold/white]

The six tray looks just like the pass side stock, same type of batt hood down clamp, try just looks like a mirror image of pass side tray. The alternator regulator is mounted in a different manner with the aid tray, and maybe other stuff on that side. I have aux trays for both my C 10’s. Since neither are currently runners, I don’t have all the details. I just plan to run2 batteries, for more cranking power, nothing to do with a camping type setup.

[bwl101]

Good tire choice! I believe those are the Destination XTs right? I put those on mine, hopefully mine will be back on the road soon to test them out. My wheels were 15s so I went with a 30x9.50R15 with my XTs. I have them on my Tahoe as well and they have been a GREAT tire!

[dagnabbitt]

Originally Posted by bwl101

Good tire choice! I believe those are the Destination XTs right? I put those on mine, hopefully mine will be back on the road soon to test them out. My wheels were 15s so I went with a 30x9.50R15 with my XTs. I have them on my Tahoe as well and they have been a GREAT tire!

I have to say you have a "good eye", that is exactly what they are, and I like them so far. Ride nice and I think that they suit the truck!

[rickcdewitt]

I've always liked those ol 6.2s. Take it easy on em and you aren't as likely to have catastrophic issues.
You said you were gonna do the front main seal?if so great time to put a fluidamper balancer on it. Those motors go through dampers and its bad when they go out

[dagnabbitt]

Originally Posted by rickcdewitt

I've always liked those ol 6.2s. Take it easy on em and you aren't as likely to have catastrophic issues.
You said you were gonna do the front main seal?if so great time to put a fluidamper balancer on it. Those motors go through dampers and its bad when they go out

I will have to read up on those, not familiar with them.

[rickcdewitt]

On second thought they are 500$lol

[68panelman]

Really neat truck. As for your rear brakes, check the hose that drops from frame to axle, might of collapsed internally. Good luck with it!!!

[dagnabbitt]

Thanks I will check that out. I also have no emergency brakes so I might have a lot of questions answered when I take it apart though.

[dagnabbitt]

Well, the taking it apart saga continues. Pictured below is the rear brake drum which we hammered on for about an hour and a half, wiggled it here and there, and finally were able to get behind to release the shoes.

One of the things I often find when I buy a really interesting, well built truck is that somewhere in the span of time between the builder and myself there is someone in between: a PO who is a real doofus who lets the truck go to seed and tries all kinds of dumb short term fixes. It stands to reason that a 50 year old vehicle will go through this cycle, maybe a few times. Well, his work here is evident.

The rear brakes were non functioning... because they were non functioning. Someone put brand new shoes on drums that had not been turned since Nixon was in office, and the result was that the new shoes were ruined quite quickly.

The ridge that was left from the gouges in the drum locked the shoes in place, preventing the removal of the drum itself. Once we knew what we were dealing with the other side came off a little quicker just because we knew where to hit it. It was pretty annoying, but of course I went through a similar experience with the drums on my 68 C20, so I had no right to be surprised. I have no idea what people have against brakes. I like them. I never, ever complain about having to buy brakes, batteries, or tires, I am not a rich man but I really enjoy replacing those things.

That said, I did ask if these drums were worth turning and got a real are you crazy, how cheap are you vibe, so new drums and whatever else is required, it is.

I have not exercised the park brake cables yet, but one is kinked and overall it would be kind of surprising if they were not seized too. But we will see.