The Stovebolt Site Forums The Shop Area General Truck Talk Rear end gears

Hi,
Another question, I have a 235 with the 3 on the tree and was wondering how to find out my rear end gears. And what would the top speed be?

Thanks,

Kyle

GM rear ends are stamped with identification on the axle housing. If you are standing at the rear of your truck, the ID number should be on the top side of the axle on the right side of the differential cover. Take the ID number and look in a GM Vintage ID Number Manual for the gear ratio of the rear end.

If the manual is not available, pull the differential cover off the rear axle. Count the teeth on the pinion gear and the ring gear. Divide the number of teeth on the ring gear by the number of teeth on the pinion gear. This will give you the gear ratio of your rear end. For example, 41 teeth on ring gear and 10 teeth on pinion gear would be 41 divided by 10 equals 4.10.

This is the most reliable method because the ring and pinion set up could have been changed, therefore the ID number stamped on the axle housing may not match the original set up.

Best of luck.

Hello Kyle,
I find it really hard to find the numbers Tony is talking about due to dirt and rust. I never did find them on my 77 Camaro rear end even after hitting with the cup brush and wiping it down with solvent. To get a rough idea of what the gear ratio is simply jack up the rear end and turn the drive shaft over a couple of times counting the number of turns the wheels makes.

Top speed for your truck is 80 Km/H on the highway, 50 Km/H in the city unless otherwise posted!

I found mine on the driver's side tube facing straight back on my 64. The 72 rear I have in my other 64 is stamped where Lilred66 described. Brian