open drive line 40 banjo rear to 36 trans.?

Friend wants to build a hot rod using a 36 flathead 36 trans. on 32 rails with a forty rearend and open drive line. We know they make an adaptor to go to the rearend but what kind of problems do we get into conecting to the 36 trans.?

32 closed drive will not bolt up to the 40 banjo so we believe we have to go open drive line to get the length right since the 40 tube would be to long.

First time on this site so i would appreciate direct e-mails if possible.

Thanks. Bill

Do you have both rearends?