Axle ratios

I'm trying to determine the axle ratio in my 1995 Z28; I am the 2nd owner without contact with the first. I understand that there was an optional gear
ratio available and would like to determine which one is in this car. I don't know whether I have the 2.73 or 3.23. Can anyone here tell me how to find this out?
I'm seeing some RPO definitions (whatever that means) as GU4 - GU6 from a parts manual. Are these codes from a VIN? I'm wondering if the information I'm looking for is somewhere on the car itself. If I can get a clue as to how these codes are read, I think I can figure out much about this vehicle.
Thanks for any help....
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The codes you are looking for are posted on the drivers door. Look for a sticker just below the door latch mechanism. - Gary

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Possibly 3.42s..............

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One of the fastest ways to get the axle ratio is to jack the rear end off the ground. Place a chalk mark on the drive shaft. Have someone turn the rear wheel 1 full turn & count the number of turns the driveshaft goes around. (If its 3 even turns the ratio is 3.00 If its about 3 & 1/4 turns it would be 3.25 or it your case it most likely would be the 3.23 ratio. Lastly if its only 2 & 3/4 turns it would be your 2.73 ratio. Big Duke

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