part no. VS. cast no.

LH 1971 B & E-body 340 C-body 360
3418620 VS. 3418621
RH 1971-'73 A B & E-body 340 C-body 360
3418624 VS. 3418623

LH 1973-'74 B C & E-body 340/360
3751083 VS. ???????

WAG ^ this unknown casting number part is what you have