1989 GMC 6000 Pickup/Toy Conversion

[Bigdually]

In this thread I'll post the pictures I have up to the current date of my progress converting an unsuspecting 2.5 ton truck into my own version of the ultimate Squarebody dually. One summer on a trip as a kid years ago I saw a crew cab C60 that someone was in the process of converting to a pickup. I knew from that moment that someday I just had to have a truck that cool! Time passed, and in July 2019 I found a beautiful rust free dually bed off an 83 GMC for sale in the town where I work. A rarity here in WV. I bought it with the intent to resell it originally, but the idea of building a big square truck crept back into my head the longer I looked at the bed.

The next week I stumbled across a dirty, grimy GMC 2.5 ton beginning to grow into the weeds about an hour from my house. I suspected it had been a toter or a tow rig of some sort due to its short length, and other than surface rust from the problematic GM white paint peeling, it was in terrific condition. Markings showed it originally came from Georgia, which I attributed its condition to. After some negotiating with the owner, I bought it and two days later caught a ride to where it was with my girlfriend and fired it up, gassed it up, and drove it the hour home.

These are the first pictures I took of it before I even bought it, I'll post more and continue the thread up to date as I go later on. Gotta go to work

[Pvmt-Pndr]

That is surprisingly clean! Nice truck! I bet a good scrub down and it would clean up very well. I like the story, you bought a bed that led to buying a truck, sounds like something I would do too. What's the power plant?

[Maytag906]

Nice ride, good luck with your project!

[Bigdually]

Originally Posted by Pvmt-Pndr

That is surprisingly clean! Nice truck! I bet a good scrub down and it would clean up very well. I like the story, you bought a bed that led to buying a truck, sounds like something I would do too. What's the power plant?

Thanks! It is clean, it washed up really nice! I have more pics I'll post later on. It has a 366 with an SM465

Originally Posted by Maytag906

Nice ride, good luck with your project!

Thanks!

[Bigdually]

After a good blasting with the pressure washer a lot of the gunk came off and I was left with a pretty clean truck. I discovered someone added AC, still haven't put that all together to see if it works. I began the small tune up and tinkering items, getting all the dash lights working and just driving it some to feel out what it needed.

[Bigdually]

One thing I discovered nearly immediately was that with a rear end ratio of 6.17, it was really humming at 45-50. I knew a gear swap was in order and I began the search. I ended up settling on a remanufactured differential geared at 4.63. Cruising at 70 MPH is now possible and the truck is altogether more fun to drive, though a gear between 3rd and 4th would be nice. The SM465 is pretty wide in ratio.

[sweetk30]

nice clean start

the rear spring hangers dont look correct to me . they look like c-10-c30 style hangers and someone has used them for this application and there not designed to be slipper hangers ether . so be sure and check this out on your build up .

[Bigdually]

Originally Posted by sweetk30

nice clean start

the rear spring hangers dont look correct to me . they look like c-10-c30 style hangers and someone has used them for this application and there not designed to be slipper hangers ether . so be sure and check this out on your build up .

Thanks!

They didn't look right to me either, but after some research it turns out that at some point it was shortened, perhaps with the idea of making a pickup out of it because it was EXACTLY the right length for the axle to be centered under the wheel wells of my bed. Whomever did it simply knocked out the hanger rivets and moved the rear end forward on the frame rails, and to get pinion angle close they moved the rear ones upward. They're the same as I've seen on lots of other medium duty GMs, a rear slipper hanger with a bump pad and a bolt below to keep the rear end from falling out should the rear of the frame be raised. The front ones do have an eye also, the tire blocks it from being seen in the picture that shows the springs

They DID, I noticed, leave the overload bumpers off. On this rig I highly doubt I'll ever be near needing them though

[Pvmt-Pndr]

Good catch on the springs.

What's the plan for it aside from putting a bed on it. It seems like this truck was waiting for you since everything lands perfect and the hard stuff is done.

If you're going to use it like a regular pick up pull some leafs out and put a set of air bags on it. I can't tell h oe many leafs you have currently because the angle of the pictures. It'd be the best of both worlds. I haven't decided if that's the route I'm going to go or not with mine. I also have onboard air too.

[Bigdually]

Originally Posted by Pvmt-Pndr

Good catch on the springs.

What's the plan for it aside from putting a bed on it. It seems like this truck was waiting for you since everything lands perfect and the hard stuff is done.

If you're going to use it like a regular pick up pull some leafs out and put a set of air bags on it. I can't tell h oe many leafs you have currently because the angle of the pictures. It'd be the best of both worlds. I haven't decided if that's the route I'm going to go or not with mine. I also have onboard air too.

I pretty well plan to use it as a normal pickup, and for some towing. I'm not too sure that I can pull leaves as simply as a normal spring pack, on these medium duty trucks it seems half the pack comes into the whole from each end. It actually doesn't ride TOO horribly, just a hair stiffer than a one ton truck in my opinion. One thing this truck does not have is an air compressor, which is alright with me but would be nice to have at some point. Air horns would be fun

[Bigdually]

After I got the gear swap done it was time to get down to setting my bed on the truck! After some measurements and figuring, I came up with a subframe made from 6" channel bolted to the truck frame and a couple cross members welded between. Then I used a 1" piece of vulcanized rubber (hockey pucks!) as body mounts for each mounting point on the bed I was pretty happy with the results of this, and the body lines ended up being nearly spot on.

I enlisted the help of my dad, my girlfriend's dad, and my girlfriend's brother in getting the bed manhandled up that high and onto the truck. First couple pics are of just after we set it on. The next is of the subframe, pay no mind to the slag and rust. Everything is coming apart and getting cleaned up and painted when the truck is taken back apart for paint at some point. The final couple show the lineup.

[Bigdually]

Setting the bed on left me with another issue, a crazy looking hitch sticking way low and way back on the truck frame. Plus with the bed my sweet trailer taillights were looking a little ugly So obviously, it was first things first, swap the huge truck steering wheel out for a nice Sierra Classic wheel! After that critical modification was completed, I ever so gently sawzalled the excess frame, which made the rear end look better instantly and was highly satisfying. After that it was onto the less fun but just as satisfying task of making all the lights work on the bed. That part for me really made it seem like a whole truck, not just a medium duty chassis with a bed sitting on it.

[Bigdually]

After this, while driving, I noticed that on long hills and under hard acceleration I seemed to be running out of fuel. Some fuel system maintenance showed why, the poor filter had to be about to collapse! I fixed that right up, and installed a wonderful new Edelbrock 650 with an electric choke and a dual feed line to replace the worn and overcomplicated factory Holley. No more running the float bowls dry now

Also around this time my amazing girlfriend bought me a bedmat for the truck for my birthday. She's definitely a keeper!!

[Pvmt-Pndr]

That looks awesome! I put the same carb (manual choke) on my 427 and was instantly impressed at the difference.

[Bigdually]

Originally Posted by Pvmt-Pndr

That looks awesome! I put the same carb (manual choke) on my 427 and was instantly impressed at the difference.

Thanks! It took shape pretty well, I keep tinkering and getting it closer and closer to how I originally envisioned in my head. The carb was probably the best thing I did to it mechanically, their pitch about the throttle response with the annular boosters is really no joke!




The next thing I did was correct my wheel and tire situation. I bought the truck with 4 22.5 wheels and new looking 9R22.5 steer tires on the rear. It had two 19.5 wheels and probably original little 8R19.5 worn out tires on the front. I discovered that the tubeless original Accuride 22.5s are EXTREMELY hard to find. And I also learned that these medium duty trucks have a very odd small 10 bolt pattern that Alcoas wont fit. Having 4 already, I turned to Wheels Now, Inc. and got two of their reproduction wheels. These are exactly the same dimensions as the Accurides, but the face of the wheel is a lot more broad and flat. This didn't concern me too much, as I could just hide them on the inside rear and have 4 matching wheels facing the world.

I took it to a local tire shop who I always deal with, and ordered 4 new 10R22.5 Firestone drive tires, and told them to take two of the good steer tires on the rear and move them up front, then put the two new wheels and tires inside on the rear and two of the old 22.5 wheels and new tires on the rear. I kept the two spare good 22.5 steer tires. That really set the truck up in the air some more and gave it exactly the amount of very slight forward rake I was looking for.

[Bigdually]

Right after the tires, my girlfriend's dad found me a really nice 12" drop bumper off of a Squarebody. I had been on the hunt of one for a long time, and they're harder and harder to get as nobody manufactures one anymore that I could find. We installed it at his garage, I think he was as excited as I was!

I also added, just before I did tires actually, stainless mirrors and arms to replace the rusty crappy white ones. I plan to find at some point a chrome grille and front bumper too, and also to install an antenna windshield with the chrome trim around the seal.

[Bigdually]

Soon after the bumper I finally got the fender clearance lights I'd ordered long before, and stuck them in. My entire goal for this truck was always to make it look like GM had produced a medium duty pickup truck. I had never seen the rear end of one that looked exactly how I'd envisioned that to be, they most usually included a rollpan and some sort of heavy steel below that and a hitch hanging way down that look more at home on a flatbed or a dump truck. I took measurements and modified the hitch that came on the truck when I bought it to fit up mostly out of sight and right below the bumper. Just like I'd imagine the factory would have built one. In my opinion, this makes for a much cleaner look from the rear.

I did, however, have a minor setback when I broke my finger because I dropped the hitch on it while installing it. That was seven weeks ago today, and only two days ago the doctor released me to go back to work.

[sweetk30]

DAM

love the rear bumper . its kind of what i based my bumper off style wise that i built from scratch .

[Bigdually]

While I was off work, I managed to use one and a half hands to build some mudflap brackets and install some flaps. I couldn't just hang them down from the rear of the fenders like a regular dually because they'd hang down into the tires. I moved them back where everything cleared, then bent some polished diamond tread "splash guards" to connect the flaps to the rear inside of the dually fenders. It's not ideal, but it works and keeps road dirt and water spray from shooting up between the flaps and the bottom of the fenders.

[Bigdually]

Originally Posted by sweetk30

DAM

love the rear bumper . its kind of what i based my bumper off style wise that i built from scratch .

That's a great looking plow rig! I really like that bumper. It's simple, functional, and it looks good too!

[CarolinaHD]

You wanna sell those 2 19.5" wheels?

Looks great keep the pics comin! You should paint the the whole truck to match the bed, pinstripes and all.

[Bigdually]

That brings everything pretty well up to date on the truck build. I have driven it quite a bit and always get lots of waves and looks, and a few horrified stares. It runs and drives great, I even put it in the Christmas parade in my hometown a few weeks back!

My next steps are to wire up my trailer plug and install a brake controller. Then after that I really want to work on a set of steps similar to the driver side one, but stretched from the front fender clear to the rear one. Maybe out of polished diamond tread. I'd also like to either put a fuel tank behind those steps or somehow under the bed and maybe run the filler neck to one of the fuel doors in the bed. After that it'll be time for paint and lots of fun cruising it around and towing tractors/whatever else I need to haul.

[Bigdually]

Originally Posted by CarolinaHD

You wanna sell those 2 19.5" wheels?

Looks great keep the pics comin! You should paint the the whole truck to match the bed, pinstripes and all.

I definitely would have, but I just did that very thing two weeks ago to a guy who runs a local tow company.

Thank you for the compliment! I have given serious thought to that very idea, I like the stripes!

Thinking also about this paint scheme, maybe yellow and white.

[Airdirect]

Really nice looking truck! Love the look of the rear bumper. The original paint scheme with the white center panel would look awesome.

[Bigdually]

Originally Posted by Airdirect

Really nice looking truck! Love the look of the rear bumper. The original paint scheme with the white center panel would look awesome.

Thank you! I have to admit the rear bumper is one of my favorite parts. From behind it comes up from the center at the same angle as the underside of the dually fenders, and it all just flows together in a way I am super happy with.

I'm leaning VERY hard toward painting it factory scheme and colors, the body lines on these just lend themselves to that combo IMO.