Genuine Ford 8.8 31 Spline Positraction unit or Traction Lok (posi) carrier with 4.10 gears. Comes with races, carrier shims, pinion bearings and original pinion crush sleeve. Races and shims are marked and with original bearings and crush sleeve setup should be a snap. Gears and bearings are real nice. 10-41 stamped on ring and pinion. It’s up to you whether or not you want to change out the bearings or not. The pinion shaft lock screw, washer and pinion shaft are also included.