Are all the TH400 to cross member mounting points the same? The cross members available for thirgens to adapt a TH400 say they need to be short shaft. If I got a long shaft and swapped it out for a short shaft I wouldn't want to run into a problem where the mounting points on the case are different and it wouldn't work.

 

Yes they are different.
Th-400 short shaft face to mount is 26-3/4"
TH-400 long shaft face to mount is 28"

Overall length is 26-3/4" on short shaft, and 34" on long shaft .

So no, you can not do as you planned, you will run into mount probs. I guess you could weld a plate steel tab to crossmember and drill new hole, but will still have torque arm mount trouble.

If the crossmember/kit mounts TQ arm to tailshaft it will not work, if crossmember has TQ arm mounted to it the longer trans may hit mount point or TQ arm

 

you might find good info in this link;
http://www.maliburacing.com/auto_tranny_id.htm

i could be wrong, but i thought the tranny mount doesnt change no matter what tailhousing you use?

 

On some they do and some they don't. TH-350 long and short tail has the mount in the same place, but the th-400 does not

 

Thanks for the info guys, but I found a short shaft tranny. I should be good to go.