psyaddict

Hi! Does anyone know where to find part numbers for internal parts to these gearboxes? I was told that rx8 5spd box can be used in t2, the guy is using it on a 20b... I need a new box and since its very hard to find a t2 box here but rx8 boxes are available i need to know if i can atleast use some internal parts.
Any help appreciated.
Also does anyone know the difference between 13 rew and 20b rear irons?

Thanks