which diff - 95 Z28

How can I find out which differential my 1995 Z28 has in it? I'm not the original owner and I've recently learned that there was a factory performance option for the final gearing. The car has the 4 speed automatic.
Thanks for any leads....
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There's a couple ways...
The easiest would be to look up the RPO code in the glove box and find out which axle it came with stock. Although the rear gear still could have been changed later on, so that's only going to tell you what it came with stock.
The only sure way to know what's in it now is to jack up the rear, put a chalk mark on the axle, then count how many rotations of your tire it takes to make the driveshaft go around one complete revolution. For example, if you have to spin the tire 2 and 3/4 times, then you have 2.73 gears, etc.

automatic.
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x-no-archive: yes
Thanks very much. I'll look in the glove box and perhaps check the physical rotation. I doubt the grears have been changed just by the fact that the rest of the car seems to be box stock.
Doomie wrote:

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You have it backwards.. Turn the tire one time and see how many times the driveshaft spins. That is if you have a limited slip differential.
If you have an open differential, it's a little harder to do. You need to either turn both tires at once or hold one still while you turn the other. In that case, the driveshaft will turn twice as fast so if you turn the tire one revolution and the driveshaft turns 5.46 times, you have 2.73's.
The absolute way to get the gear ratio is to pull the cover and count teeth.
-Bruce
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I believe stock Z's came with 3:42 with the 6-speed, and 2:75 with the automatic. Once again, the only sure way to find out is with the RPO in the glove box (assuming it's still stock).
Rob

automatic.
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the
I can only speak for '98+, but auto's could have 2.75's or 3.21's (if I remember correctly, could be anywhere in the 2.7X or 3.2X range, respectively) depending on options. I'd have to check my RPO reference to be sure, but it's not in a convenient location at the moment... heh heh
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GU2 Axle, Rear 2.73 Ratio GU4 Axle, Rear 3.08 Ratio GU5 Axle, Rear 3.23 Ratio GU6 Axle, Rear 3.42 Ratio
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-OR- if the gear selector has a 1 indicator its a 3.23, if not it's a 2.73
a wrote:

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