304 V8 Three Speed to Four Speed Swap

[CJ SuperChief]

Hey Guys, I'm a newbie to the forum and just picked up my latest project vehicle, a '77 CJ7 with the AMC 304 V-8 and three speed manual. This thing was a single owner vehicle and sitting in a barn for the last five years. Lots of work to do on it. I'm wondering if there is a four speed out there that would be a direct replacement? Any ideas?

 

[mtnwhlr]

I'd go with the T-176 . I'ts a good strong stock 4speed.

 

[jscottk70]

I replaced my T-150 in my 79 CJ AMC 304 with a T-18A. It was a direct replacement and optional in 79. If you can find one, you will also need the 4x4 shifter that came with a Model 20 Transfer Case paired with a T-18A. The T-18A is longer than the T-150 and moves the Transfer Case back a few inches. The stock 4x4 shifter will be too short. You will also have to lengthen the front drive shaft and shorten the back.


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[HackFabrication]

I'll second the move to a T-176 . I'd also look for one that's hooked up to the Jeep bellhousing and the Dana 300 . You're not gaining anything on the street by going to the T-18 over the T-150 . However on the trail you are getting that 'granny low' first gear.

 

[Dolamite]

I'd recommend researching the final drive ratios for your rig.

This is an awesome site where you can play with different tranny's, transfer cases, differential ratios, and tire sizes:

Gear Ratio Calculator

I have a T-176 tranny and I like it a lot.

 

[Neuner]

3rd? for the T-176 /T177. If you decide to go that route and look for one, make sure you get the adapter along with it for connection to the Dana 300 . Some sell it separate for extra money.

 

[JR74CJ5]

OP - Really depends on what you want out of this rig...

You want a road queen? You want a wheeling / Road Combo? You want a off road mostly?

I wheel mine, not a direct replacment by any means, but I swapped a SM420 in for the lower granny low.

Others have mentioned some good options though - T-18 or T-176 / 177.

Some info for you:

T-176 The Novak Guide to the Tremec T176, T177 & T178 Transmissions

T-18 The Novak Guide to the Borg-Warner T18 & T19 Transmissions
(Careful - not all are the same...)

SM420 The Novak Guide to the GM Muncie SM420 Transmission
(This is extensive swap. Not a direct swap in. Only really worth it if like me you want a exptremely low first gear. Effectivly still a 3 speed on the road...)

Point is - Transmission swap is never "EASY" - just some easier than others. But figuring out end game before tackling a swap, may help you in the end from doing it twice...