Overview
The Alloy USA 21105 is a one-piece AMC Model 20 rear axle shaft with 29 splines. It fits the 1976-1979 Jeep CJ7 and is made for 76-83 Jeep CJ Quadratrac applications.
The shaft is made from 1541H or 4140 steel, heat treated and induction hardened, and it is up to 35% stronger than stock. The 21105 has 29 splines, so the differential or carrier it works with must use the same spline count. Confirm your CJ has the Quadratrac setup before ordering.
Key features
- One-piece replacement shaft for the AMC Model 20 rear axle
- 29 spline
- Fits 76-83 Jeep CJ Quadratrac
- Alloy USA says its shafts are heat treated and induction hardened
- Bearings, seals and studs are not included
- Axle: AMC 20 rear
- Axle shaft location: Confirm the side on your axle before ordering (position rear left)
Quadratrac and CJ drivetrains
The Quadratrac setup on a CJ changes how the rear axle is loaded, so a shaft that works in a standard CJ may see different stresses. Before buying, confirm the setup under the vehicle and check the side needed on the axle. Measuring the old shaft for spline count and length gives a quick check against the new part, and it helps avoid a return after the job has started.
When the shaft is removed, look at the splines, the bearing seat and the retainer for wear. Clean the spline ends and fit new bearings and seals if the old ones show play or leakage. Keeping the axle cover, breather and gear oil in good condition helps the new shaft last, especially on trail rigs that see deep water or steep climbs.
- Confirm the Quadratrac setup before buying
- Measure the old shaft’s length and splines
- Clean the spline ends before fitting
- Replace worn bearings and seals with the shaft
Specifications
The 21105 is a one-piece replacement axle shaft for the AMC 20 rear axle, with 29 splines. Every figure in the table below is the manufacturer value for the 21105.
| Brand | Alloy USA |
|---|---|
| Part number | 21105 |
| UPC | 70000531011 |
| Part type | One-piece replacement axle shaft |
| Axle | AMC 20 rear |
| Axle shaft location | Confirm the side needed on your axle before ordering (rear left position) |
| Spline | 29 spline |
| Manufacturer part number | ALY21105 |
| Application stated | 76-83 Jeep CJ Quadratrac |
Vehicle fitment
The manufacturer fitment list for the 21105 names: 1976–1979 Jeep CJ7.
Application: 76-83 Jeep CJ Quadratrac.
Measure the shaft you are replacing and compare it with the 21105 listing for spline count, length and side.
Confirm your vehicle’s year, model and trim before ordering.
Installation notes
None of the bearings, seals or studs are included with the 21105, so check the condition of the old ones during the swap. Its side information conflicts between the feature list and the attributes, so confirm the side needed before ordering.
What’s included
One axle shaft.
Not included: Bearings, Seals, Studs.
