cody ethridge

I have a 5spd in my 75, obviously its not factory, how would it know what type of trans it is and where would i find a rebuild kit, also would it be more benificial and cheaper for me to just find another 5spd trans, ive got 4sps i could put in it but id rather have a 5spd. also i was reading earlier that the earlier 240s have shorter driveshafts. If this is true could i put a t5 from a zx wit a short drive shaft?