The Stovebolt Site Forums The Shop Area Engine Shop 1958 3/4 ton Apache Stepside

I am in the process of having the engine overhauled in my truck (6 cyl 235). I have been driving it daily but the engine has been working hard to keep up to the traffic. The four speed is just not the best thing for a daily driver with 17 miles of highway driving each way. I would like to either put in a five speed transmission or re-gear the rear end. What would be the best way to proceed.

If it is a 2 wheel drive, placing a Tremec 5 speed, or even a 6 speed shouldn't be that hard. Just need an adaptor bell housing and a shortened driveshaft. Someone will chime in about what bell housing to use.

Good luck.

I would try to get a 4.10 pumpkin from a 67-72 3/4 chevy automatic.

If you can get the 4.1o pumpkin, that is a good start. Find an OD transmission, and that will be even better. There are several OD trans that can be made to work. The tremec listed above is probably the most expensive.

I would not reccomend a t5 in a 3/4 ton truck, but that will likely be your cheapest option... again I think it may not live long in a 3/4 ton truck.

The A833 4 speed is another option, a litle more than a t5, but a much more solid transmission. 1st, 2nd, and 3rd match up pretty well to 2nd, 3rd, and 4rth of the sm420 you have. 4rth gear is a 0.73:1 ratio giving you a 27%OD. With this transmission you would lose your granny low, but gain the OD.

The NV4500 is another option a little more pricey than the A833. This is a really tough transmsion. 1st gear is a little bit higher than the first gear of the sm420... 5.61:1 compared to 7.05:1. 2nd, 3rd, and 4rth, are roughly equilivant. 5th is a 27%OD. The 1994-1997 Dodge 2wd NV4500 is the easiest version of this transmission to adapt to a stovebolt because it is the only version that can accomodate a mechanical speedo gear.

There are other transmissions to research, but these will give you plenty of reading. In the end, you have to decide which one fits your needs and budget best.

John

I installed a Tremec TKO 500 (TCET 4616) in my vette this spring and after running it a while I can honestly say they are worth the dough imo. I'll have one in the '58 someday.

It's a fairly straight forward swap that matches well with the chevy. Input shaft and bolt pattern are correct, so you can use a stock bell housing (on a V8, not sure about a 6). There are a wide range of shifter locations available. They also come with both a mechanical and electronic speedometer drive.

My long term plan for my 55 2nd was to install a t5, but this a833 and nv5400 sound interesting. How about the GM bolt pattern? Will these fit with no modification or do you need some type of adapter? What about the yoke and driveshaft? Thanks for the info.

Hugh

6 cylinder and 8 cylinder bellhousings look the same to the transmission in 1958. The transmission mounting pattern was used by gm for a long time... from about 1947 on in trucks, and after 1960 for cars. The sm420 truck transmissions were made by "Muncie"! A Muncie transmission such as the M21 and M22 has the same mounting pattern. Some transmissions may require using a different clutch disc.