* 8.2-inch ring gear: This was common, often with a 2.73, 3.08, 3.31, or 3.55 gear ratio.
* 8.5-inch ring gear: Less common than the 8.2-inch, but possible, particularly in higher-performance models.
To know for certain, you'll need to:
* Inspect the rear axle itself: The easiest way is to remove the differential cover and count the teeth on the ring gear.
* Check the vehicle's documentation: If you have the original build sheet or other documentation, it might specify the axle ratio, which indirectly tells you the ring gear size (though not directly). An axle code is also sometimes stamped on a tag on the rear end.
* Look at the vehicle identification number (VIN): While the VIN doesn't explicitly state ring gear size, decoding it can sometimes give clues about the options package, which might suggest a likely gear ratio.
Without physically checking the rear end or finding original documentation, it's impossible to say definitively what size ring gear is in your specific 1971 El Camino.
