USA Standard Axle Shaft For 80-90 4Wd GM Truck

Heavy-Duty Rear Axle Shaft for 1980 to 1990 Chevrolet and GMC 4WD C/K 1500 Trucks with GM 8.5in Rear Differential

The ZA G14039547 from USA Standard Gear is a direct-fit replacement rear axle shaft designed for 1980 through 1990 Chevrolet and GMC C/K 1500 four-wheel-drive trucks equipped with the GM 8.5in rear axle. Measuring 31 1/2 inches in length with a 28-spline count and a 6-lug wheel flange, this shaft restores proper power delivery from the rear differential to the wheel on these capable full-size 4WD trucks. Produced from 1541H alloy steel, the ZA G14039547 provides the tensile strength and fatigue resistance required for trucks that carry loads and navigate challenging terrain.

This shaft fits both Chevrolet and GMC C/K 1500 four-wheel-drive trucks across the full 1980 to 1990 production run. USA Standard Gear backs the ZA G14039547 with a 10-year limited warranty against manufacturer defects, so you can trust the quality of this replacement shaft in a demanding truck application.

What's Included

• 1 x USA Standard Gear ZA G14039547 Rear Axle Shaft

Specifications

Vehicle Fitment

Why This Shaft is the Right Choice for Your Square-Body Truck

The 1980 to 1990 Chevrolet and GMC C/K square-body trucks are among the most enduring and sought-after classic trucks on the road today. These vehicles were built to work, and the GM 8.5in rear axle in the 4WD configuration was a key part of that capability. USA Standard Gear understands the demands placed on these drivetrain components and engineered this shaft to meet or exceed the original equipment specification. The 1541H alloy steel construction means the shaft handles the combined stresses of towing, off-road driving, and daily use that these trucks were built for.

The 6-lug wheel flange matches the factory bolt pattern on 1980 to 1990 C/K 1500 trucks, ensuring wheel compatibility is maintained after the replacement.

Frequently Asked Questions

What vehicles does the ZA G14039547 fit?
This shaft fits 1980 through 1990 Chevrolet C/K 1500 and GMC C/K 1500 four-wheel-drive trucks equipped with the GM 8.5in rear axle.

Does this shaft fit both 2WD and 4WD versions of the C/K 1500?
The ZA G14039547 is specified for the 4WD configuration of the C/K 1500. The 2WD and 4WD variants can use different shaft lengths due to differences in axle housing width. Verify the shaft length of 31 1/2 inches against your original shaft before ordering.

What is the spline count on this shaft?
This shaft is machined to a 28-spline count, which is the correct specification for the GM 8.5in semi-floating rear axle in 1980 to 1990 Chevrolet and GMC 4WD trucks.

What bolt pattern does the wheel flange use?
This shaft uses a 6-lug wheel flange, matching the factory configuration on 1980 to 1990 C/K 1500 trucks.

What material is this shaft made from?
The shaft is produced from 1541H alloy steel. This material combines high tensile strength with good fatigue characteristics, making it well suited for truck axle applications that see frequent loading and occasional off-road stress.

Can this shaft be used on a C/K 1500 with a Detroit Locker or locking differential?
Yes. The shaft interfaces with the carrier side gear, and the locking or limited-slip function of the carrier is independent of the shaft selection. Confirm the 28-spline count matches your carrier's side gear before installing.

What warranty comes with this shaft?
USA Standard Gear provides a 10-year limited warranty against manufacturer defects on this shaft. This warranty is structured in compliance with the Magnuson-Moss Warranty Act. Retain your purchase receipt for warranty service purposes.

Does this shaft fit the C/K 2500 or C/K 3500?
This part is listed specifically for the C/K 1500 with a 31 1/2-inch shaft length. The C/K 2500 and C/K 3500 use different axle housings and may require a different shaft specification. Verify the shaft length and spline count on your specific application before ordering.

How do I confirm my C/K 1500 uses the GM 8.5in rear axle?
The GM 8.5in rear axle was standard equipment on most 1980 to 1990 C/K 1500 trucks. You can confirm this by reading the axle tag on the driver-side axle tube near the differential, which lists the gear ratio and build date. Counting differential cover bolts (10 bolts in an oval-like pattern) or referencing casting numbers on the housing are additional ways to confirm the axle type.

Installation Instructions

1. Safely raise and support the vehicle on rated jack stands at the rear axle. Remove the wheel on the side being serviced.
2. Remove the brake drum (drum brake applications) or the caliper and rotor (disc brake applications). Secure any brake components so hoses are not stressed.
3. Remove the differential cover bolts, remove the cover, and drain the gear oil into a container.
4. Remove the pinion shaft retaining bolt and slide the pinion shaft out of the carrier.
5. Push the axle shaft inward to expose the C-clip groove at the inner end, then remove the C-clip.
6. Slide the old axle shaft out of the housing. Inspect the axle seal and bearing; replace any worn or damaged components before installation.
7. Insert the ZA G14039547 into the axle tube, aligning the 28-spline inner end with the carrier side gear. Push inward until the C-clip groove is accessible inside the differential housing.
8. Install the C-clip on the shaft groove, then pull the shaft outward until the C-clip is firmly seated against the side gear.
9. Reinstall the pinion shaft and lock bolt, torquing to the factory specification.
10. Clean the differential cover mating surface and reinstall with a new gasket or RTV sealant. Torque cover bolts evenly in a cross pattern.
11. Refill the differential with the correct gear oil type and quantity per the GM specification for the 8.5in rear axle.
12. Reinstall brake components and the wheel. Torque lug nuts to the specified value.
13. Lower the vehicle and conduct a short test drive. After returning, check for any gear oil leaks at the differential cover and inspect for any noise from the rear axle area.