Does anyone know of any sites or ways that I can find out that stats or what rearend I have in my 2000 C5. Anything to put my vin # in or something.

 

I assume you have an A4 (auto) transmission? If so, I believe there is a sticker in the glovebox that will show a code for the "Performance Axle" option (3.15 ratio). Since I have a manual tranny (MN6), I can't check mine, but if you look at the code and then call the dealership in your area, they can confirm. If you have an MN6 tranny, the stock final drive ratio is 3.42:1.

 

Or, you can simply jack-up the rear of the car to get the back wheels off the ground, put the transmission in nuetral, and manually turn the back wheel exactly one revolution while watching how many revolutions the drive shaft makes. If it makes close to 3.5 turns, then you have the 3.42 ring & pinion ratio in the rear. If the number of driveshaft revolutions turns out to be closer to 3 turns (with just a hair more) than you have the 3.15 gear ratio.

 

If you have the 2.73 axle ratio the shaft turns a bit less than 3 turns.

ButyYou might have trouble seeing the drive shaft turn because it is inside the torque tube on a vette. This trick works on most other cars, though. I've never bothered to check whether you can see the drive shaft turning anywhere but I don't remember being able to see it on my C5.

 

You can just take the car out for a drive, drop the trans down one gear (not in the overdrive position) and take her up to 70mph - your tach will tell you what diff you have in the car (i.e. 3150 rpm you have a 3:15, 2730 you have a 2:73 etc)