Your Q has been answered but for future reference, a B/RB 727 will have (4) 1/4" dust cover mounting holes (SB has (2) 1/4" bolt holes) and facing the front of the trans a B/RB trans has a rounded face at the ~9 0'clock position (SB is kind of flat on that side). there is also a C to C dimention difference between the two top mounting bolt holes but I ain't sure what the dimentions are.