Help with transmission decision

[drummerdad]

I am working on the frame for a 67 dodge D100, and hope to have it boxed and ready for suspension installation soon. The original frame was for a d-200 which is just a heavy duty long bed. My question is about the transmission options. I have 2 trucks and Im trying to build one good truck.

It came with a New Process 435, which is a 4 speed. They came in 2 different ratio sets. The "A" had the following; 1st-4.56, 2nd-2.28, 3rd-1.31, 4th-1.0, Rev-5.64. The "L" had the following; 1st-6.68, 2nd-3.34, 3rd-1.66, 4th-1.0, Rev-8.26. I think I have the "L" transmission. My situation is that Im rebuilding my sons truck the way we discussed it, and he wanted a manual. The truck we are rebuilding has a newer 318 with an auto. Im not really sure about which auto, but we bought a shifter and never really got it to work well. Plus the transmission leaks a little and I think it was slipping as well.

I think I have two choices, and I was wondering what you guys think. The truck will be a driver, not a racer. Itll have an IFS from Jimmys Jalopies, and a triangulated 4-link with coil overs on all 4 corners.

Here are my possible options;
1) install the NP435, with a new clutch and pressure plate, and in the future put in a divorced splitter. I talked to gear vendors at drag week this past year, and they sell a splitter for the NP435 for about $3k. This would make it an 8 speed in effect. This would use the factory clutch pedal, and factory transmission mounts, and I wouldnt have to modify the transmission cross member. I might even be able to use the original clutch fluid reservoir. I might have problems getting a clutch and pressure plate for a 50 yr old tranny though.

2) Install the auto, after making a few repairs to it. This would be temporary though. I would work to install a newer modern 6 speed, like the one from a dodge challenger (I think its a TR6060). I eventually want a newer hemi also, so this would mate perfectly. BUT, the factory transmission cross member would have to be re-worked for the auto, then re-worked for the manual in the future. I also dont know if the clutch fluid reservoir or the clutch pedal assembly would work with a newer transmission. Used the newer transmissions are going for a little less than $3k. But it would also require a new clutch and PP. Plus I dont know where the shifter would be, and Im keeping the bench seat.

I guess there is the 3rd option of installing the NP435 and get the truck on the road, and make the call about the modern transmission later. From what I have read, the NP is pretty tough, but its basically a 3 speed, because who needs a 6.68 or even a 4.56 first gear. The new dodge 6 speed handle the hellcat, so close to 700 ft lbs. This would prevent me from cutting the manual transmission cross member out.

[andrewb70]

I don't know Dodge parts very well, but wouldn't a T56 Magnum work with a proper bellhousing (QuickTime must make one for this swap). It may not be the least expensive option, but would fit with what you son wanted and be future proof for upgrading the engine down the road.

Andrew

[drummerdad]

Any modern 6 speed would work, I only plan on about 450-500 hp. The problem is I need to make a decision now between the manual or the auto. Both have issues, but I dont have the money in the budget to get a new transmission now. So I can either modify the cross member and install the auto, or leave the cross member alone, install the 4 speed and see how it works. Then make the decision later to install the divorced splitter, or a newer 6 speed.

FWIW, I removed the bell housing earlier and holy crap, that thing has to weigh 80 lbs.

[Kenova]

The T56 Magnum also offers multiple shifter mount options.

Ken

[silvermonte]

I would put the manual in now that you have. Then down the road go with some version of a t56, or a tr6060 if you could find one of them. Maybe down the road get a pull out of a wrecked vehicle and get the motor and tranny as a unit.

[drummerdad]

I would put the manual in now that you have. Then down the road go with some version of a t56, or a tr6060 if you could find one of them. Maybe down the road get a pull out of a wrecked vehicle and get the motor and tranny as a unit.

I think thats what Ill do. It gives me time to make sure the pedals and hydraulics on the truck work, and to research which 6 speed I need. The hemis come with the tr6060 (which has the annoying skip shift) but the t56 has an aftermarket. I drove a friends Plum Purple 6.4 Scat Pack, and it was a monster. LOVED that car.