2 parts listed
Part # = 54110-41300
Part Description = HUB,FRONT
Model Count = 2
RM125B 1977
RM250C 1978
and
Part # = 54110-41301
Part Description = HUB,FRONT
Model Count = 9
DR370C 1978
DR370N 1979
PE175C 1978
PE175N 1979
RM125B 1977
RM125C 1978
RM250C 1978
RM250C2 1978
RM400C 1978
perhaps one is magnesium? they did offer oprional magnesium hubs for some models