j20 transmission and transfer case - JeepForum.com

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post #1 of 6 Old 12-14-2009, 04:27 PM Thread Starter
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j20 transmission and transfer case

I will soon be looking at a 4 speed tranny out of a j20 year unknown. My question is what tranny is this? I'm sure it probably isn't an sr4 or t4. He also has a transfer case. He says they are heavy duty. with this possible combo work behind my 1981 258? I am just wanting some info before i go look.



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post #2 of 6 Old 12-14-2009, 04:35 PM
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It's probably a T18. If it is the T18 (it is) the input shaft will be too long.. you can get a short shaft kit from Part's Mike to have this work in your CJ. This is a common upgrade and I have a short shaft T18 out of a FSJ myself.
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post #3 of 6 Old 12-14-2009, 08:19 PM
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J20 should be a T18. Transfer case, if aluminum (np208), is nothing to brag about. Could be a Dana 20 if the truck is a 70's model, still nothing to brag about. The late J20 T18's are quite odd, as they are a Ford in the back(31spl, ~7" extension housing) and Jeep up front (odd mounting pattern, long input) and they also have no pto cover, it's cast into the case (Yes, I have confirmed this personally). Earlier 80's FSJ T18's are the same spline as the Dana 300, but came with a NP208, which isn't anything great. Either way, if it's an 80's model, with the long rear extension housing, it's almost better to start with a Ford T18 for a swap into a CJ.

1977 Cj5, 258, T-18, 2.46:1 Dana 20, 2.5" BDS lift, OBA, 38.5's. Chevy 60 frt, 14b Rear, Full hydro, 102"wb, full DOM cage.
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post #4 of 6 Old 12-15-2009, 05:36 AM
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The 208 is actually a nice, strong transfer case with 32-spline outputs, bigger planetaries, and a wider chain than a 231. It is also shorter and of course has the factory fixed rear output that other 208's don't.

The comments above about the "Ford" style configuration of it are correct. You don't want the 31-spline version. Like No Bs suggested, The later 80's T-18 isn't a good setup to start with.

In the event it is a T-177, it will accept your Dana 300 and work well as long as you don't have an input shaft issue.

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post #5 of 6 Old 12-15-2009, 06:11 AM
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I used t-18 out of a 81 FSJ in my cj-7. The short shaft, and the adapter to fit the dana 300 came to over 700.00. I can,t remember if the t-case was a 208, but it was a driver side drop. I didn,t know much about jeeps at the time, and was told by the seller that this combo would bolt right into my cj. After all was said and done, my jeep is on the road( 360/t-18/dana 300) and that guy is out of business.
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post #6 of 6 Old 12-17-2009, 04:46 AM Thread Starter
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Sounds like i need to pass on this one. Thanks for all the advise!!
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