I have a 2000 LS8 sport. How do I find out which gears I have?

If your build date (on decal inside driver's door) is before 7/99, you probably have the 3.58 rear, if not, 3.31 (or was it 3.32?). OR, you can crawl under the rear and look at the diff (which is what I did), its either cast or stamped on the pumpkin (or a tag, can't.... re...mem......ber).