which transmission

How can you find out which transmission do you have, idk if yall remember my other post about that shady dealer but I went to a performance shop and found some interesting shit out. like the block is a B18B1, the head is from the B20, I have a stage 1 clutch or what ever, and the tranny is pretty short ratioed. like 1st gear ends at 25mph, 2nd at 45mph third at 60mph and fourth at around 80mph so Im trying to find out what tranny I have. also whats the benifit to having a B20 head, there seems to be more airflow and Ive actually beaten a stock Gsr, murdered an Ls powered Civic hatch, and killed a mustaNG V6 moded.

if i can remember right it is an S40, i think.