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1991 GMC V3500 Project

sethgmcv3500

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Location
Leander, TX
This thread will be a series of posts on my 1991 GMC V3500 build.

But first, the backstory.

About 2 months ago my 2018 GMC Denali was stolen (hot item here in Texas and FYI, they're easier to steal than a square body...). I had been looking at adding a C6 Z06 to my fleet about a month prior to that but hadn't pulled the trigger on anything just yet. After the truck was stolen my gears switched to finding another crew cab square body and maybe an even nicer Corvette. I've had a '90 Crew, '89 Blazer, '90 burb, '73 C10, and I think that's it for the squares. I won't drive the truck much as I work from home and really just need it for Home Depot/Lowe's and grocery store runs (I only put 10k on my Denali in 2 years). After about 2 minutes of deciding this I hopped on FB marketplace and came across a 1991 GMC V3500 cab & chassis, 454, SM465. 2 days later I was making the 4 hour trek with cash to purchase. This truck came from West Texas earlier this year where it spent it's entire life on a ranch. The surface of the body clearly showed it's age but when I started pealing back the layers I found absolutely ZERO rust, I mean NONE. Other than light surface stuff here and there of course. I couldn't be happier, well maybe I could have been if it was cheaper and had a 4L80e, but it is what it is. It's the core of the truck that I've always wanted.

And just a couple weeks ago I added that Corvette to the garage, a 2013 ZR1. But who cares about that! We're here for the other unicorn!

I've had it for about 2 months so I'll try to post in order of the work I've done so far.

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First thing to go was the flat bed, rear axle, front hubs, and frame shortened in preparation for a short bed, single wheel conversion. The previous owner did this work over the summer but I grabbed some pictures so I could show the before and after. The rear axle is out of an '05 2500HD. It fits perfect, of course after the obvious modifications required like shock mounts, ebrake, brake lines, and spring perch's, but it's the perfect width for these trucks.

Shortening the frame is always a touchy subject on these trucks as there is multiple "right" ways to do it. The previous owner chose the straight cut and diamond plate method. While it's not the route I would've chosen, the welds look fantastic and the plate looks to be 3/8' or 1/2'. There's been about a thousand miles put on it since shortening and the welds still look great. Regardless, I may add some small plates on the inside bottom of the frame bridging the weld for added reinforcement.

The front hubs were even swapped with a gentlemen looking to convert a DRW setup (lucky I know).

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Now we're under my ownership.

First thing to do was begin to fix all the chewed up wires and replace every sensor and pigtail on the engine harness. Between the Texas heat and rats that must have lived on the engine at one time, the harness was a complete mess, it ran but just barely. I found every sensor pigtail I needed (all of them) on RockAuto.com. Sensors came from NAPA. Some nice braided split loom, tesa tape, and air cleaner from the Amazon and were now in good shape in the engine department.

As I began digging in to it, I found some slightly repaired damage of the core support from what looks like a very small collision with something on the ranch it came from. So, I made the decision to replace all the sheet metal on the front end. I'm not super happy with my choice in parts as the cheap aftermarket panels and core support are just that, cheap, thin, poorly formed, and razor sharp. They may all get removed and swapped with OEM parts off a donor if I can find one before paint.

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The work continues. But now it's time for some fun stuff, like a lift and tires. After countless hours of research, scouring the interwebs for how to lift this truck, and reading every opinion on every brand known to man, I landed on the below parts list... As many of you may know there is no "kit" for this truck. First off, R/V usually breaks the internet, add cab and chasses/56" rear springs, 1 ton, HA!!! Smoke will come spewing from your ethernet connection or your head. I didn't want to spend a ton on custom springs as I figured I could get the ride I was looking for if I just looked hard enough. Research prevailed when I landed on the Tuff Country's, perfect ride in my opinion. I also didn't want to spend a ton on wheels and tires. Sure there's better tires out there that could get me a thousand miles across the desert at 100mph but this truck won't see either of those aspects any time soon. When it was all said and done, it had a 1.25"rake to it (measured from back of cab to front of cab at pinch weld), but I was hoping it would be more level. I noticed my front shackle bushings were shot when I installed the lift so I ordered some new bushings and decided to get some 6" shackles sides from diy4x. Stock is 4.5" so that should bring the rake to within a 1/2" or so which will be perfect in my eyes.

And of course the age old question of "what's the biggest tires I can run with a X inch lift?". Well this setup is great and there's zero rubbing with these offsets running around the streets. When pulling in to a steep driveway or the like there is slight rubbing if I'm going fast enough. Taking it slow, it does not rub at all. The 6" front shackles will likely completely alleviate in street driven rubbing.

Tuff Country 4" springs, 35x12.50x20 Federal Couragias and 20x10 Vision wheels.

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Dang that's a sweet truck! Welcome to the site and keep posting the build! :thumb:
 
Very cool to see someone somewhat local. Im just south of New Braunfels.
If my 91 was a big block sm465 truck I'd have kept it that way. Had to lose the 4l80e.
 
Very cool to see someone somewhat local. Im just south of New Braunfels.
If my 91 was a big block sm465 truck I'd have kept it that way. Had to lose the 4l80e.

Awesome! Yea, I don't mind it except that I have no highway gear. I don't plan to drive the truck much on the highway anyway but it would be nice to have the option. It has 4.10s so it's pretty wound up at 70mph, about 2,800 rpms.
 
Nv4500 swap it. Its almost too easy on that truck.
I may start researching that swap further. Every time I go down the trans swap rabbit hole, I end up deciding that I should just get an LS 6.0/4l80e combo :rotfl:, then I go to bed at 3am and do it all over again the next evening hahhaha.

BTW, I just read your entire build thread, pretty cool!
 
Good to see another short box crew on here.
There isn't very many.
I'm hoping to shorten mine in the very near future. I miss my old sbcc.
 
I got the sport style rear bumper installed this week. This is a cab and chassis truck so some rear frame modifications had to be made. The rear most crossmember was also in the way so it will be relocated about 12” forward. Also needing modifications were the bumper brackets as the 56” rear spring hangers were in the way. If you have 52” springs then I could see how less modification would be needed. Yea, I see it's not straight, it's simply not adjusted 100% yet.

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Also this weekend I removed the manual fan and factory electric pusher fan and installed two electric fans, one pusher (in factory location) and one puller. Oddly enough, the primary reason I did this was because the engine wouldn’t warm up. You heard that right, it wouldn’t warm up... past about 130°. I have not checked the thermostat, but I have a feeling it may be modified somehow. It does work as when I removed the fan altogether before I installed the electric fans it took about 40 minutes for the truck to warm up but you could see the temp fluctuate as the thermostat came on and off some around 190°. Ambient temp was a sunny 75° day. For now the front pusher fan is wired in to the factory fan wiring that it replaced and the rear fan is installed with a simple switch under the dash. Idling around town and a 45 minute trip never required me to turn the rear fan on. I’ve never owned a vehicle that ran this cool here in Texas, although it’s not 100° right now it’s still odd to me, ha ha. I’ve verified the temp gauge is working accurately by removing the temp sender and checking the resistance with various temp water. I used cheap 14” and 16” fans found on Amazon. They’re so cheap that if they fail I won’t be upset at all... haha. I also used waterproof 30/40a relays for wiring.

Radiator is a Liland HD 39". It doesn't fit "perfect" but it's really close. Nice quality but was full of metal shavings when it arrived and was slightly damaged in shipping. https://www.carparts.com/radiator/liland/lil774aa

14" Fan
https://www.amazon.com/gp/product/B073WM5RKH/ref=ppx_yo_dt_b_asin_title_o08_s01?ie=UTF8&psc=1

16" Fan
https://www.amazon.com/gp/product/B01MTLGP1Q/ref=ppx_yo_dt_b_asin_title_o08_s01?ie=UTF8&psc=1

Waterproof Relays
https://www.amazon.com/gp/product/B089776XVQ/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

Let me know if y’all would like any more details!

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Fan clutch eliminator, is partially to blame for long warm up. Also no trans cooler in rad.
That the same radiator as pre full electric fan?
Cool Vette.
 
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