Is it an MT-12 or an MR-12?
If you don't know, pull the motor apart and look at the piston. If the bottom edge of the piston skirt is even all the way around you have an MT-12. If the side of the skirt facing the crankshaft is cut out a bit then you have an MR-12.
Sean. Certified speed crazed mowron.
Team Shepherd USA