Duramax 2500HD '58 Panel
 

I realized maybe some folks on this GMT800 side of the site might be interested in my current project.
I had a very good condition 1958 GMC Task Force panel just itching to be a hotrod. It's a 3800, which is a 1-ton 3500 in todays models.
But I wanted reliability included and wanted to keep the load rating.
I searched for a number of years for a suitable donor - found the LB7 Duramax unicorn, flew out, drank some wine and drove her 1,000 kms home to Victoria BC. A one-owner mint 2001 Chev Silverado 2500HD 4x4 Duramax with the ZF6 6-speed manual trans.

Re: Duramax 2500HD '58 Panel
 

A couple more pics of the '58 Task Force body - it is originally blue, used by a mining company in Northwest Territories. No salt up there, so trucks are in amazing shape. I sanded and stripped the red down.
I cut the '58 floor and firewall out keeping the important parts like the hood hinge mounts in anticipation of a donor vehicle - the wait was 3 years.

Re: Duramax 2500HD '58 Panel
 

The front clip is a '55 which came with the truck. Some pics of the '01 being cut apart.
I wanted the GMT800 floor, seat bolting, dash electronics, air bags and structural integrity.
The under dash brace bar which ties the A-pillar posts together was able to stay.
Thats the '58 hubcap on the '01 steel wheel. I've not seen these wheels before, but I like them as they have a vintage look.

Re: Duramax 2500HD '58 Panel
 

We sold our house with my garage lift, so now had to come up with a rig to allow the body to be lowered a bunch of times to figure where to best cut.
I have an excavator, they are great for strength but lack finesse, so I had to build a rig to keep the body from swinging around - it actually worked well.
Those steering wheel air bags sure are a bugger to pull - there are 2 pins needing released which keep snapping back when you try the opposite side.

Re: Duramax 2500HD '58 Panel
 

Are those GMT 400 or GMT 800 wheels? I like the look with the hub caps.

That's a nice donor vehicle to start with, you just gotta make sure the end result is as nice now lol

Re: Duramax 2500HD '58 Panel
 

@connorm, I kinda figured they were GMT800 spare tire wheels, but after looking at a number of 2500's, I changed my mind. They are flat enough to (almost) fit inside the '58 TF body lines, and it's cool how the vintage hubcaps fit on them.
I am trying to make the recessed 3500 dually wheels work on the truck - here are my real-world test mock-ups. Love the look.

Re: Duramax 2500HD '58 Panel
 

the wheels in question

Re: Duramax 2500HD '58 Panel
 

@connorm, I see we have similar tastes in GMC long boxes. Yours looks great with the 2500HD wheels. It's a '71 GMC 3/4 ton Sierra Grande, cousin of the Chev Longhorn. It has the 8'6" bed on a factory 1 ton frame with 3/4 ton 8 lug running gear, hence the extra 6".
Right now I'm just running it and bombing around the property once in a while. It has the wood bed, but its rotted out. Future project.

Re: Duramax 2500HD '58 Panel
 

I spied that truck in the background. That truck has an awesome spec, the GMC Longhorn with the medium olive/dark olive has to be one of the best combos.

I actually want to take the GMT800 PY0's off and put a more period style wheel on my truck. I have actually thrown around wagon wheels, whether they are white or chrome. If only you could buy 8 lug wheels that were 16" or 17" that weren't $350 a piece.

Re: Duramax 2500HD '58 Panel
 

I like the look of the dually rims, you could event do that all the way around. Some of the early 17" split rims that were used on railroad trucks, along with other mostly industrial applications, were high offset wheels. A similar look to the wheels mocked up in this post

Re: Duramax 2500HD '58 Panel
 

Subscribed, can’t wait to see where you go with this project!

Re: Duramax 2500HD '58 Panel
 

I never thought of those railroad recessed wheels - I would assume they were all 8 luggers as well.

Re: Duramax 2500HD '58 Panel
 

Some more progress shots -

Re: Duramax 2500HD '58 Panel
 

The wheelbase is perfect. Playing with the height - trying to get the body as low as possible.
The mounting surface around the perimeter where the factory caged nuts are is already 2-1/2" below the 2500HD frame rail - and the cross beams are not installed yet

Re: Duramax 2500HD '58 Panel
 

I made up some body mounts on the ‘01 HD frame similar to stock and mounted the new 2” square tube body subframe and installed Suburban 2500 Energy Suspension bushings.
The square tube subframe is bolted to the stock task force body mount points around the perimeter with the factory caged nuts. The weight of the body bears on the square tube subframe which in turn bears on the body mounts to the frame.

Re: Duramax 2500HD '58 Panel
 

It took 2 sheets of 4’x10’ 3/4” birch plywood.
Seam is positioned so the original metal runner strips will cover.
An 8” hole was cut and a flush thru-hull threaded hatch installed for access to the fuel pump.

Re: Duramax 2500HD '58 Panel
 

The factory ’01 heater requires a fresh air intake from the cowl.
The '58 task force cowl takes air into the cab a different way down from the A-pillar sides.
Had to cut the cowl open and create a new plenum, blocked the ends and added drains on each side so the '01 heater would work properly and block the driver side off as well.

Re: Duramax 2500HD '58 Panel
 

Onto the fuel filler - the ’01 tank is on the left side vs the task force right side location.
I chopped up my parts truck ’03 Suburban and welded in its fuel door.

Re: Duramax 2500HD '58 Panel
 

on to the front -
I fabricated up a 1” tube frame to mount the '01 rad, intercooler, ac condenser in the (almost) stock locations. It took a few attempts.
I copied the ’01 front aluminum rad cradle in steel, with body mounts to the frame, so it could be welded to the 1” square tube frame. All the stock ’01 sensors were installed in the correct locations on the new cradle.

I trial fitted a dual electric fan to allow the rad etc to be located closer to the motor, but they really are not that much thinner and reasoned to keep the stock clutch fan for reliability as everything was able to move rearward about 2”.
A reasonable space was left between the rad and the clutch fan.

Re: Duramax 2500HD '58 Panel
 

The Duramax intercooler is so large, it would not fit behind the stock grille location for sure.
I figured a body mod would be easier (and much cheaper) than a custom remote intercooler set-up as some folks have done, and as well, keeping the short direct ducting, so the grille surround was cut out and moved forward 2-1/2” and welded.
It looks ok and in fact is hard to distinguish as to what’s different.

Re: Duramax 2500HD '58 Panel
 

I also incorporated the inside hood release from the ’01 !

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The dash.
I initially wanted to keep the ’58 dash, but wanted all the Duramax electronics to remain.
At the moment, I decided to fit the ’01 dash and drive it for a bit to see if I like the combination of old and newer. It certainly is a shock to see such a modern dash in the ol' girl.
The fitout was a bit complex but not overly hard.
Both outer vents have to be moved due to cutting the dash about 2-1/2” off each side.
The outer right side vent fits in a space beside the ‘01 glovebox which required the glovebox door to be shortened. Sectioned a 3" piece out and used the soldering iron to melt the end back on.
The left outer vent fits where the light switch was, which was moved to the center lower cover under the ashtray after soldering extra length to the wires. These trucks all had auto lights anyways, so the location is fine.
More to come.

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Dash top
I purchased the cheapest planishing tool from amazon.ca to (try and) build my dash top. The quality of the dies are very subpar and they do not provide matching male/female dies. The only hammer end provided is flat.
I attempted a number of times using the planishing hammer and ended up with a number of unusable messes. I went back to the tried and tested ¼” steel rod bird-cage frame and bent up multiple short pieces of sheet metal to weld up. That worked well , but a lot of work to clean-up to make smooth. The result though is great. This dash top is able to be unbolted now for access.
I modified the '01 wiper support and had to mount under the dash inside to accommodate the '58 linkage. Works great - and I get to keep the factory stalk controls.

Re: Duramax 2500HD '58 Panel
 

I hid the dash hold down bolts under the 'D' and 'R' DURAMAX letters.

Re: Duramax 2500HD '58 Panel
 

Playing around with a shifter, really want something hot rod, long and original.
One of my favourite cartoon characters, Squidwards' head is the perfect shape for the knob.
I grabbed one of the old '58 bearing caps and pounded it into shape over a trailer hitch ball in the vise and welded a long 1/2" nut into the middle. For the nose, eyes and brows, I just mig welded at low temp/hi wire speed for build up and ground smooth. Painted it up, it looks amazing! Kind of like a new Rat Fink character.
Here are the various shifter sticks I am contemplating - the left of course is the factory '01 ZF6, the next is the '58 shifter, next is '58 emergency brake handle, and the right is th '58 pto handle.

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Door Locks:
I wanted the ’01 door lock mechanisms and factory remote fob capability.
Had to fab some pivot brackets to allow use of the ’58 exterior door handles which push instead of pull. The problem was converting the inward push of the thumb button to straight down for the latch module within the limited space inside the back end of the door behind the door window rear vertical track.
By chance, the ’01 lock module is vertically U-shaped, perfect to fit around the window track. The ’58 interior door latch handle and flat metal linkage stays stock except for the end drilled to accept the modern thick wire linkage and connectors.
They work great. The doors close real smooth and soft now. The 2 doors took approx. 3 days to figure out and complete.
At this point I am leaving the rear door as factory manual lock only.
The factory fob works perfect, one push driver door, 2nd push passenger door lock opens.
A problem with the ’58 door key, is that the key only deactivates the thumb push. Its function does not extend beyond that – meaning that when the power door locks are locked, you still cannot open the door with the key.
You can lock the door via the key though, even with the power lock unlocked.

Re: Duramax 2500HD '58 Panel
 

The lights were a bit tricky, as I wanted to retain the ’01 light wiring and bulbs, connectors etc for reliability.
I used a hole saw to drill out the middle of the stock task force front indicators to graft in the ‘01 indicator twist-in bulb housings and modern 3157 bulbs. Go J-B weld.
It all fits with the stock mounting bolts to the body.
For the headlights, I bought new headlight units with the replaceable H4 bulbs and installed LED bulbs.
Found a wiring conversion harness which converts the ’01 dual 9005/9006 hi/low beam wiring to the hi/low beam single H4 bulb. Really simple plug and play mods to convert from 4 light set up to 2 light setup. They are super bright.
The rear tail lights with the single small bulb were again cored out to accept the 2 separate brake and turn signal bulbs. It works and looks great!

Re: Duramax 2500HD '58 Panel
 

Finally received the windshield after 4 months. Installed it myself as not a single shop in my area would take it on. I will say, a factory gmt800 windshield is 100x easier! Good workout though.
Then it was off for BC's out-of-province inspection to get on the road.

Re: Duramax 2500HD '58 Panel
 

I believe those are Dodge wheels from 90's trucks and vans.

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Awesome find, thanks @bnorth! I see the matching wheels on ebay . . good to know.
It's neat that the 1958 era hubcaps fit. I'm gonna add some retaining screws just in case though.

Re: Duramax 2500HD '58 Panel
 

Passed the out of province inspection - forgot to install the upper fan shroud, and the aftermarket windshield squirters do not fit the factory bezels - smaller thread. They made me clean up some loose wiring at the foot well. As the windshield squirters were not mandatory in 1958, they passed it. Used the same plates off the '01.
This beast drives amazing.

Re: Duramax 2500HD '58 Panel
 

I posted in a separate thread re: collapsed plastic gmt800 clutch pedal. I will add here as well.
Being a little robust with shifting, my clutch pedal suddenly twisted down to the right while pushing on it.
I had to pull over. I went upside down and managed to push the pedal straight - it turns out the pivot 'bolt' plastic spring loaded mechanism gave way, not the typical master cylinder pulling through.
Strange how such a strong workhorse gets a plastic clutch pedal - the most used pedal of the 3.
Found out KB Diesels makes a real metal clutch pedal for gassers 5 speed and ZF6 6 speeds.

Re: Duramax 2500HD '58 Panel
 

Finished the clutch pedal install 4 days ago. Nice metal pedal assembly now.
I bought the heim joint upgrade. Have to cut and thread the pushrod - easy enough on the truck. No disassembly required.
Allows adjustment now. Cool.
I will say, there is NO MORE FLEX in the pedal as before. Mine failed at the springed-pivot bolt. The pedal just folded sideways.
Remember this is a stock '01 GMT800 LB7 chassis/drivetrain/firewall and front floor section.