See Figure 1
The axle identification number is located either on a metal tag (attached to the rear axle cover) or stamped onto the right front side of the axle tube.
To service the rear axle, the 4th digit must be known, which is the manufacturers identity. The codes are: K for GM of Canada or G for Saginaw. The rear axle identification number must be known to order the Original Equipment Manufacturer (OEM) parts.
If the identification tag is missing, or it does not have the gear ratio stamped on it, a quick way to determine the axle ratio is as follows:
- Raise and safely support the rear of the vehicle on jack stands.
- Matchmark the inside of one rear wheel and the ground with chalk or other suitable marker.
- Matchmark the pinion yoke and the axle housing.
- With transmission in neutral, turn the driveshaft (or pinion) and count the number of turns it takes to turn the wheel one complete revolution.
- Lower vehicle.
You now have an estimated axle ratio, examples being: 2 1 / 2 turns of the pinion to 1 turn of the wheel equals a 2.50 ratio. A 3 1 / 4 turn of the pinion to 1 turn of the wheel equals a 3.25 ratio. Remember this is just an estimated ratio and the actual ratio may be slightly different upon ordering replacement parts.