877-323 883-511 Parts.Replacement part number,Framing Nailer (885-915, 877-323) - 877-323,Heat treated tool steel 6150 - Rockwell hardness 50-52,877-323 Aluminum is crimped into the grooves of the shaft to prevent unscrewing. Hardened steel lock tite and micro-mechanically locked interface. Guaranteed never to unscrew.Compatible with Hitachi framing nailer models:NV65AC Coil Pallet Nailer,NV50A1 Light-Duty Coil Utility Nailer,NV50AP2 Full Round Head, Coil,Wire Collation Pasti-Tacker Plus,NV65AA Nailer.NR83A2(S) Framing Nailer, Full Head, Plastic Strip Collation (without Depth Adjustment)NR83A 3-1/4" Full Head NailerNR83A3S Strip NailerNR83A3 Strip NailerNR83A2 Strip Nailer