This is a A-RK154-40 Piston with Rings, .040" PN: RK154-40Main Description As Following : A-RK154-40 Piston with Rings, .040" PN: RK154-40 Found in Section & Models : Engine Parts > 201 CID Gas, Ford / New Holland TRACTOR: 4600 (1975-1981) Associated Items : New Also A-FO-O-2600UP, A-FO-P-2600, A-FRM-FO-MID, A-SMFO41 And : High Quality Afternaket Shipped from Both US and Canada