Trying to mate an Audi V8 to the above box.

Input shaft length seems the biggest issue (too short).

Does anyone make different length shafts?

IIRC the ford and GM T5s use different length shafts. From 1997+ GM uses "ford" T5s in their camaros.

There are a LOT of different T5s out there. You will want to know exactly which one you have. For example my 1990 S15 truck has a T5 from a 94 S10. (shorter throw and stronger than the 1990 T5), my last mustang had a T5, and my locost has a T5. All four are completely different and share virtually no parts.