How do I know what the gear ratio on my 2001 Chevy Silverado z71 4x4 is? I know it's a 10 bolt. Any help would be appreciated.

 

If you look in the glove box, there should be a sticker containing all of the RPO codes. The ones for the rear differential ratio are there, and all start with a G if I am not mistaken. There is an RPO decoder online at https://decoderpo.com.