This pilot bushing (or “spigot bushing” as it’s referred to in the UK) is intended for use with Bugeyes and Spridgets equipped with the Rivergate Datsun five-speed transmission conversion. Two sizes available depending on the size of the hole in your crankshaft, 5/8″ (most 948-1275) and 3/4″ (late 1275). Not sure which you have? Measure the inside of the crankshaft where the pilot bushing rests, or order both and be sure!