Okay I see what is going on here. Your '85 came with a
T-5 Transmission . A PO swapped in a
T-150 and a
Dana 20 . Both the
T-5 and the
T-150 have a 7.5 inch input shaft. The
T-150 is a much stronger tranny but it only has 3 speeds.
Saddle Tramp is right, installing a Ford
T-18 will be easy to mate to your bellhouseing. The problem is the
Dana 20 . The Ford
T-18 has an output shaft that inserts into the TCase. The
Dana 20 expects the tranny to have a gear on the output of the tranny. This whole gear fits into the TCase when they are mated. The ford
T-18 will not easily mate to your
Dana 20 . If you still had the
Dana 300 it would work. You would still need an adapter. I have done that swap with an '82
CJ7 .
Saddle Tramp is right again that finding a Jeep
T-18 will be less messing around. It will mate up to your
Dana 20 without a hitch. The problem is now mating it to your bellhousing. A
T-18 from a FSJ will have an input shaft too long. The link
Saddle Tramp gave says a CJ
T-18 will work. That will be hard to find. Call around and search the internet for a CJ
T-18 from the '70s and remember you need a Jeep
Transmission with a 7.5 inch input shaft and a gear on the output of the tranny. It may be hard to find but it should be an easy swap. No adapter will be necessary but your drive shafts will need to be modified.