The Stovebolt Site Forums The Shop Area Driveline New guy with '38 GMC 1/2 ton looking for advice...

Hello All, I have spent the last several months reading and lurking after I purchsed our '38 GMC 1/2 ton project on just what to do with it now that I own it. I'm sorry for the long post.
Right now, original drivetrain is there, the 223 Pontiac, 4 speed and the torque tube. I want disc brakes and to be able to go highway speeds should the need arise. Instead of spending any money on making the engine a runner after sitting for 60 plus years, I thought of going with something that has more power to make it more practical to use for a quick trip to the harware store or haul something every now and then. I'm thinking of a 270 and would like to have a 302 but not in the budget also ran across a really nice 228 ready to go which is as good as new. I have also located a 270 from a '48 big truck, with 4 speed and a PTO from a local farmer who wants $350 for it all and he says she runs fine when he took it out of a grain truck 5 years ago... Anyway back on topic.
I have located a s10 tranny with mechanical speedometer and the slightly better world class T5 from a 305 for cheap that I thought of meshing together but recently learned of the dodge 4500 swap which sounds like the top of the line of swaps?
My question is in level of difficulty is there much difference in effort and/or cost using the nv4550 versus the T5 other than the cost of the transmission ? Then I'm still in the market for a rear that will go under it. I want disc brakes but not sure if I can mount a modern master on the frame for that early of a truck I've seen them for the AD trucks? Then do I stay 6 lug or go 5 ? I'm in the planning stages now and want to do it right the first time. Thanks for reading that long winded post and look forward to your opinions and thoughts.

Hy oz07, welcome, I'll deal with the tranny first, for a half ton the T5 should be more than adequate, the NV4500 is really a medium duty truck transmission, and would be overkill in a half ton. A lot of rear axles that didn't come from the factory with disc brakes have kits available to convert them to disc brakes, just look around at the various brake suppliers, and make note of what kits are available, and then you can zero in on an appropriate rear axle. The engine is totally your choice, lots to choose from. Now to the safety aspect of driving a 1938 designed vehicle at todays freeway speeds, suspension and steering upgrades should definately be considered. One more thing you might consider, transferring the body to a more modern chassis, quite a few AD trucks have been mounted on S10 chassis, hope that helps.

The 270 would be an excellent choice for the engine.

I wanted to keep the stock look; tires, wheels, hubcaps on my 1939 GMC, but have the safety of disc brakes and be able to cruise at highway speeds. After a lot of deliberation I went with a 270 engine, T5 transmission and a disc brake rear end out of a 2002 4WD Blazer. The rear end is the exact same width as the stock 1939 rear end. Just have to move the spring perches to install.

Originally I was going to have some wheels made; 16" with the 5 lug 4-3/4" pattern, but I couldn't find any that looked right and the stock hubcaps would work. I wound up sending my front & rear brake rotors and rear axles to Moser Engineering in Indiana. They welded up the stock lug holes and redrilled to the stock 6-lug pattern so I can use my original wheels.