Quarter Midget Gearbox - Gearbox Part #’s. o QBX-1000-YH for Honda GX, Yamaha YF/MZ and “Clone” engines from 120cc’s thru 200cc’s and o QBX-1000-BS for Briggs and Stratton Animal/World Formula 206cc platform. • The internal reduction is 3.86/1 and fits those engines listed above with a .750 by 2.300 straight shaft and 3/16 sq. keyway. • The gear housing and cover are made from aircraft quality 356-T6 castings and the internal shafts and gears are made from heat treated 8620 Alloy steel and precision machined on modern CNS mills and lathes. • Components all ride on precision high capacity ball bearings. • The output shaft is a .750 od 11 tooth spline which insures a nice true running sprocket and eliminated the need for a key in that area. • Gearbox is complete with engine and sprocket mounting hardware and 8 oz of light viscosity gear lube.