I'm in the market for a 3/4 ton 8.1L Suburban or Yukon XL. Obviously most of the sellers don't list the rear end, nor do they know. Can I tell from the VIN? If not, how can the seller easily find out for me?

Thanks!

I Believe it's in the RPO list in the glove box, What year is it?

Here’s RPO codes:
http://www.c2e.info/rpocodes/gmrpocodesGthroughM.html
http://www.c2e.info/rpocodes/
http://www.angelfire.com/ny2/96transam/rpocodes.html

OR

-Jack both rear wheels off ground
-Spin driveshaft, (counting the revolutions), until rear wheel spins one revolution.
For a 4.10:1 gear ratio, the driveshaft spins 4.10 times to turn rear wheel one turn.

I know it used to be in the glove box with all the little numbers GT4 or GT5 I belive GT4 is 373 ratio and GT5 is 410 ratio.

Right on guys, thanks! I'm looking between 2001-2006. Those are the years they made the 3/4 ton Suburbans with the 8.1L engines. They have a tow rating of 12,000 lbs which should be perfect for me.