The 1229F222 is a World American differential side gear thrust washer, identified by the interchange marking RT40-4N. It cross-references to FRTS5007, FRT-S-5007, and 60171331, making it a direct match for shops replacing those numbers. This thrust washer sits behind the differential side gear to control axial clearance and manage rotational friction inside the differential carrier. Stock the correct part number to keep your rebuild on spec.
Features
World American part number 1229F222
Designated RT40-4N differential side gear thrust washer
Cross-reference to FRTS5007 or FRT-S-5007
Also interchanges with 60171331
Fits between the side gear and differential case to manage clearance
