how to determine which rear end i have? also, how many springs should a 1500 have? someone said 3, my 1500 has i think 5, not really sure, but NOT 3 for sure. Is there a way to determine what type it is? by vin? also what axle? its whining a little, but it has been since i bought the truck.

I borrowed this info from one of the other threads here and the owner gets credit for it at the bottom. Look at the sticker in your glovebox and find the code that corisponds with the ones below, and that will tell you your ratio.

Check out the build sheet in your glovebox.

GT4 3.73 (most likely)
GT5 4.10
GT7 3.33
GT8 4.10
GU2 2.73
GU4 3.08
GU5 3.23
GU6 3.42
GV2 5.83
HC4 4.56
HC7 5.13
HE3 3.07
HF7 4.56
HF8 4.88

GT4 is the most popular ratio by far, you won't find most of these ratios any where near a Silverado, but I just threw them in anyway.

-salcker

As far as your springs go, it depends on what towing package you have..

Check out this link. It is probablly a GM 8.5" 10 bolt. I was looking for this for my 01 SIlverado.

http://www.drivetrain.com/GMtrkratio_posidata.html#differential%20cover