Other models may also be compatible but these are the definites.
Part # = 510-11412-01-00
Part Description = CRANK (LH)
Model Count = 3
IT400C 1976 400 IT400 Dual-Purpose
MX400B 1975 400 MX400 Off-Road
YZ400C 1976 400 YZ400 Competition Motocross
Both crank halves, crankcase halves, barrel & head are from the same models