Car 4 speed to truck 4 speed swappin'

[TrikeKid]

So I inherited my dad's flat fender recently. This Jeep was built to race more than wheel in the early 80's, current powertrain is a Chevy 153 backed by an early iron case T10 adapted to a Dana 18. This works pretty good when you're ripping around barrels on 27 inch tall Goodyear Xtra-Tracs but it makes for a real miserable crawl ratio even for the 31s it has now, especially since I'm pretty sure it's got the stock WWII t-case that has a 2:1 low range.

The most expedient remedy I've come up with thus far is yanking the T10 and replacing it with a SM420 or 465 to get the extra low gear, but even the normal first gear in either one is lower than the current setup. Are GM 4 speeds standardized to the degree that I can bolt the truck transmission up to the current bell? I looked around parts catalogs enough to see that the clutch splines are the same but info on the early T10 is all buried by info on the later models.

 

[jawzjeep]

Cant help without pics. Im lying. I cant help anyway. But pics are still cool.

 

[TrikeKid]

Cant help without pics. Im lying. I cant help anyway. But pics are still cool.

I need to get some pics underneath for relevant info to the thread but this is it as it sits. It'll get a thread in the Jeep forum once I get a little farther along on the revival.

 

[jawzjeep]

Bored so im looking. Found this? They're just going reverse.

 

[total newb]

If you want to use your existing bellhousing you need to use the sm420.

 

[PAE]

I used a m21 4 speed transmission in a 71 CJ5 with a Dana 18 about 40 years ago with a AA adapter to make the rear of the m21 adapt to the Dana 18.

Worked really well for that project, YMMV.

 

[total newb]

You mean your jeep you never rock cralwed in.

Your m21 and his t10 have nearly matching 1rst gears, which specificaly what he is complaining about.

 

[TrikeKid]

If you want to use your existing bellhousing you need to use the sm420.

Definitely like to leave all that alone since it looks like it's some kinda old school scatter shield that the clutch linkage is all built to work with. The SM420 setup ends up a little longer than a 465 but if I don't have to fuck with the current working clutch setup that's fine by me.

Found one for $50 on the local craigslist, snagging it in the morning. Even if I have to do bearings/seals along the way a 50 dollar transmission and the adapter is still cheaper and slower than Teralow gears on their own let alone wrangling up a large hole D18/D20 case around here.

 

[TrikeKid]

Waiting to crack it open at work but the little bit of oil it dumped out in my truck seems average-ish and wasn't water so off to a good start.

 

[rugburn]

I have the IDENTICAL SM420 here.
Been hoarding parts for 20 plus years 🍻👊🏼😎

 

[plym49.2]

How you gonna connect the SM420 (it's a 2WD version, yes) to your TC?

I need to connect mine to a 231 but the Novack/AA adapter kit price tags have me wheezing.

 

[TrikeKid]

How you gonna connect the SM420 (it's a 2WD version, yes) to your TC?

I need to connect mine to a 231 but the Novack/AA adapter kit price tags have me wheezing.

Novak adapter. It's $$$ but I'm not gonna wait around forever on a used one.

 

[total newb]

How you gonna connect the SM420 (it's a 2WD version, yes) to your TC?

I need to connect mine to a 231 but the Novack/AA adapter kit price tags have me wheezing.

Well thats how its done.