AMERICAN MADE BY THE ORIGINATOR This 2-bolt rear mount is made of super high tensile alloy to be virtually indestructible. Slips over studs and starter shafts on completely assembled motors and frames. Gusseted on the top (rather than the bottom like stock mounts). Mount is heavily reinforced in all areas that tend to crack, even under normal stress. Studs on the motor must be removed on split cases. 52-56 K MODEL (STOCK USES 4) 57-66 (STOCK USES 4) 4 BOLT MODELS MAY NEED SOME CASE GRINDING 67-81 (STOCK USES 2) Harley-Davidson motorcycle frames were not perfect since they twist when welding and you may need to shim your motor in the frame because of this.