Hemi 4 Speed?

They both have 18 splines. It is the tailshaft/mounting i am concerned about. I plan to use one of them, i am fabricating a hot rod and can make the trans mount to fit either transmission (the tailshafts are different). What i am afraid of is that i have an original transmission for a hemicuda and i'd rather get that one into the hands of somebody that needs it and make my trans mount for the other transmission. I don't know the numbers for the proper hemicuda tailshaft. I asked Bucky Hess about it and he recommended that i come here (he is an automatic guy).
Thanks, i appreciate all the help, oj