what 4 speed do i use

hi all i have a truck that i was going to put a 4 speed granny box in but not sure what tranny i have 2 one says borgwarner on the side the other says T 18 on the side these are cast into them and each one has a groove where the clutch disc fits on the shaft not sure if that means anything or not.
both came from behind a 351w and are in great shape just not sure witch one is better or not thanks