I use a 3550 in mine. I have a Bennett racing 351 svo stroker 505hp/485 torque in mine. The 3550 holds up just fine. I would recommend mcleod all the way. Don't under build the car it will come back to bite you in the as$ with more $$'s. Both John Bennett and Brian @ B & B said that tranny will handle the motor without any problems... so from there on out it becomes driver error.