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Q: Rear end

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I need to know what kind of rear end I have in my 1981 chevy pickup. I have the vin number. I hope it has a 4/10 rear end.

A: Hello. On a vehicle this old, it is virtual...

Hello. On a vehicle this old, it is virtually impossible to tell what gear ratio was originally installed in your trucks differential, or what may be in there now. New vehicles tend to have a metal tag attached to the differential with the ratio stamped on it. You can determine what ratio is in there now with a simple test. Securely block the vehicle so it can't roll in neutral, raise one rear wheel just off the ground so it can be turned by hand (or both if you have a limited slip differential).

Rotate one rear wheel so that the tire valve is at it's lowest point to the ground. Put a chalk mark on the driveshaft where you have a good visual reference point to something that does not move (i.e. bracket). Rotate the driveshaft as many revolutions as required to make the tire complete 1 revolution, counting full and partial driveshaft revolutions as you go. Four revolutions of the driveshaft, plus a bit more, would be your 4/10 ratio rear end.

You may went to get in contact with a local dealer if you need further help having this checked.

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