Use in stock replacement applications on 45" models and Big Twins.
B757 Fits 1936–1964 Big Twins (OEM 60555-36)
B758 Fits 1936–1964 Big Twins (OEM 60572-36) B758A Fits Paughco #’s B770 and B770A for 45" primary covers (OEM 60569-29)
OUTER PRIMARY COVERS
B750 Fits 1936–1954 4-speed Big Twins without compensating sprockets (OEM 60505-36) B751 Fits 1955–1964 4-speed Big Twins with compensating sprockets. Fits 1936–1954 models if a Paughco #B752 inner primary cover is used (OEM 60505-55) B770 Custom style for 45" two or three wheelers with kickstart B770A Stock style for 45" two or three wheelers with kickstart (derby cover attached to primary and two inspection holes) OEM 60504-32