It's a 1974 version Fox 36 bushing, Fox cat. no 13600.
All Fox 35s started out with the same mounting bolt pattern. The cases on the 1960 needle bearing combat specials, the ones with the removeable front ends, were pretty weak. By 1962, Fox made the bottom end of the case thicker, thus inceasing it's outside dimension and the bolt pattern width, from 1 1/2" to 1 5/8". There after all the 29Xs, Rocket 35s, 36s, and combat specials have had the wider case and wider pattern.