i was wondering if all 91-96 parts off the 13b are interchangable like the rotors,and housings?

 

Most every part interchanges, but you can't intermix. IE if you want S5 rotors then you have to use both rotors, the s5 front counterweight and the s5 flywheel/rear counterweight.

What specifically are you looking at doing? Is this n/a or turbo?

 

The turbo rotors are interchangable, the turbo housings are also but you need to block off the coolant ports on the S5 turbo housings, if you want to put a 13brew housing in your S5 TII you wont have the coolant ports.

The NA S5 rotor housings work perfectly if you switch the exhaust sleeves.

The NA S5 rotors, NA S5 irons, and TII S5 irons are not interchangeable with the REW(93+) engines.

Other than bearings/stat gears everything else is interchangable.

That should clear it up for you.