Originally Posted by vintage chromoly

The mr is not the same as the alpha. It came out before the alpha and is interchangeable with the alpha.

I have an mr behind a warmed up 188 (302 ford) mine makes around 300 hp and is in a 1975, 19 foot, searay.

Mine has held up fine with yearly gear lube changes. No hole shots or air and it will survive behind a 300 hp smallblock.