Buyig a 4spd trans

If I can get ahold of the guy tonight I will be buying a 4spd trans with bell and shifter..

The question is tho.. how do i know what im buying and if it will work on the 360 im building. what are splines and how many do i need and whats a good casting number or numbers to look for?

is there a chart i can print that will let me know..

he says its out of his 318 cuda.

Thanks
-Jeff