i did an om 616 in an 87 wrangler with a t18 ford 4sd and a 1356 transfer case. This is much easier than making all those adapters and you can can the ax15 trans. I will be happy to answer any questions anyone has. Also my jeep is for sale if anyone wants to do it the easy way.

 

I like you idea but most are trying to do it the cheapest way possible buy using their original parts. I know alot of people said the 5th gear in an AX15 is useless unless on flat ground but why would you want to go backwards and use a 4 speed? What year and model would you get the t18 and 1356 T-case from and how much would it cost? I really do like your idea just trying to figure out which is easier and cheaper!

 

The only reason 5th gear would be useless is you have the wrong gearing in the axles. With this motor you need 411 or lower depending on tire size. I have 30in tires and 411's, od rocks!!

 

I was meaning useless without a gear change but did not say that. I don't want to use a 4 speed but this info could be useful!

 

Hmmm, the stock gearing for a 2.5 Jeep diesel with the AX-15 is 3.73, max rpm 3900. And I still reach 110 mph with ease.
Tire dimension used is 235/75 R15. 31" gets a bit sluggish, but who cares? 5th gear is useable anytime.

 

235/75 r15's are 29"

 

yupp, tried the 31" also.
235 is no difference to factory 225. But a "real" half inch taller, .
To much road use- 31" makes no sense to me.

 

You guys have made sense to me about 5th gear and tire combinations but I'm more interested in the rest of the post.

 

IIRC, the T-18 is worse than that. It's the sister to the NP435, and as such is a 3 speed with a granny low gear (crawl) at the bottom.
I have my concerns about the torque of a diesel running thru a car transmission, but 3 actual speeds seems like a step backwards, IMHO.

 

With the 616 engine (which is the only one that will work properly in a wrangler the 617 wont clear the front axle without some kind of lift or crazy angle) and 29" tires 5th gear would be usless. My t18 is from a 81 f250 with a 460. I used it because it was free but I would never use the ax15 unless it was the only thing I had most jeeps you will find cheap have a bad ax15 in them. I wanted a 100% reliable swap and the t18 will last forever in this application. If you want to change gears all the time maybe you need a 5 speed or with some 4.56 gears I could use overdrive but it is geared just like the 240d i pulled it from now 3speeds on the road is enough and i have low when i need it. Its a perfect combo for me. I have it out right now switching to an external slave cyl and installing a 617 turbo. Then ill see if it can pull 31's.