Tranny help

The existing tranny in my '68 is supposed to be a T90C based on the markings, mated to my 225 V6. I get the feeling it is about to go, and I was wondering what possible differences there may be with this one, which is mated to a buick V6 (?? on which V6) in my parts vehicle. I think this one should be ok, but it was installed and never run. I would still like to give this new one a shot if possible. I have yet to even see the '65, so i have no idea on which V6 it is.

 

I am sure someone will chime in here, and I think you are asking what the differences might be between a T-90 A & C model? I think there were possibly different ratios. As some were in Scouts, Jeep trucks and wagons as well as CJs.
I would take the shifter cover off the new one, and take a looksee. If it looks ok, I would pull them both and see if they swap, start her up and stick it in gear.

 

Thanks. I have read on the possible gearing differences, but did not know if input shafts could have any variation. I planned on pulling the OD off of this one, and putting on my TC, but I am thinking I might enjoy the twin sticks from this one (and I think my transfercase may go along with the tranny). Once I get the chance I guess I will pull the whole setup, have someone more qualified than myself inspect/repair/replace gaskets on the tranny, TC, OD, then swap all new in.

My eventual plan is to make one really nice CJ5 from the two, but for now I would like to just get by.

edit: after thoroughly reading some old threads, I guess it is impossible to have a T90C mated to a V6, unless is was essentially converted to a T90A. So, unitl I count teeth I will save any decisions.

 

so the t90c is the "long-shaft" version? ... without reading thouroughly through the old threads

 

That's an aftermarket adapter which requires the long input shaft. That rules out the T90C, since it can't accept the long input. I believe this is what you were referring to Mike?

The long shaft is from the T90J (??) used in trucks. T90A and C have the same input shaft length but different gearing.

 

Yeah..

 

Well, I climbed under my Jeep and used a mirror and flashlight and scraped off the gear oil on the side of my tranny case. It is marked a T86AA (which is what would be expected from the factory), but has what I can only assume to be an original T90C shift cover. My dad bought this Jeep with 52,000 garage-kept, low impact miles, and I doubt anything had been swapped. So, my guess is they used whatever shift cover was in hands reach at the factory.

 

I haven't read anything definitive about this lately, but somewhere I read that the T86 is a T90 with a helical 1st gear. May be some other internal differences. The stock T86 top cover may have T90 cast in to it, just like some (all?) T18 covers have T98 cast in.