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Discussion Starter · #1 ·
i'm working on a '78 cj-7 with a small block chevy in it. I'm currently running the original three speed with model 20 t-case. it's running 4.56's and 35's and i want it to be a little more highway friendly while still using it as a weekend toy. I want to know if I'll have any trouble running a 700r4 and what transfer case will i need?
 

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Get em as a matched set. You're gonna add a lot of length to your drivetrain also, so a wheelbase extention may be needed also.
 

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You need a 208 or even better a 241. If your front axle is a drivers drop use a 241c. The 208 is 2.6 to 1 and the 241 is 2.7 to 1. Go to the web site below and plug in all the info it will let you know what changes the diff trans and cases will make in RPM. It's a cool chart.

http://www.grimmjeeper.com/gears.html
 

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Discussion Starter · #4 ·
its a passenger side drop t-case, will i really need to extend my wheel base? i don't really want to cut into the body tub, but i guess i'll make the sacrifice if i have to.
 

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its a passenger side drop t-case, will i really need to extend my wheel base? i don't really want to cut into the body tub, but i guess i'll make the sacrifice if i have to.
Measure your trans and T case and I'll measure mine. Then you'll know about where everthing is going to land if you do the swap. I have a 700 with a 241.
 

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I take it with the 20, the rear in the that 78 is not offset? Also, I have heard the 20 will work with a 700r4 if you shorten the shaft some on some of the 700r4s but I have never tried it.
 

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Discussion Starter · #7 ·
Measure your trans and T case and I'll measure mine. Then you'll know about where everthing is going to land if you do the swap. I have a 700 with a 241.
i'm at 27 inches from front of bellhousing to the end of the yoke. its a t-120 trans with a model 20 t-case.hacck
 

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Well, if you're looking at 24" with just the tranny, then you are gonna end up with probably over 40" with the 241 behind it. I don't have the parts to measure, but both peices will be longer than what you have now.
 

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Just took a rough measurement on the 700R4/241 combo in my 90 Suburban. It's right at 4-feet to the back edge of the rear output tail housing. :shock:
 
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