OLDER Models this will fit are:
880710 to 880723 (not 880721), 881007, 881419, 881860, 881862, 881864, 881867, 898318, 898400 to 898418, 898500, 898501, 898502, 898504, 898506, 898516 and more.
Some of the newer models this will fit:
898440-443, 898458, 898459, 898532, 898437, 898450, 898451, 898461, 898454, 898434, 898435, 898444, 898455, 898456, 898457, 898540-544.
The 898452, 898530, 898531, or the 898535, those take the 3/4" bore master cylinder cushman part #886875, but this will mount up just exactly the same.