Which rear end do I have ??
 

The book says they are 2 different rear ends and there is a big difference in the towing weight they can pull. There are 2, one is 3.42 and the other is 3.73, so how can I tell which one is in my 2000 silverado 1500 5.3 V8?

4wd or no?

It's a 2 wd

The easiest thing to do is call your local chevy dealer and give the service guy your vin. they can pull up the options code sheet for your truck. The rear axle ration is on that sheet. Have done this for several of my trucks.

Bein 2wd in 2000, probably 3.42. But some 2wd came with 3.73s

Jack up one rear wheel.

Turn the tire exactly two turns and count the number of times the driveshaft rotates.

Allan

Check your RPO codes in the glove box and check it against this list
Rear End Gear Ratio for Chevrolet, GM | Ring and Pinion Gears | Chevy Ring and Pinion Sets | Drivetr - Drivetrain.com

rpo# axle ratios
gho 3.54:1
gt4 3.73:1
gt5 4.10:1
gu4 3.08:1
gu6 3.42:1
hc4 4.65:1

This is the sticker inside the glove box and the sticker on the door. I don't know which is the RPO code your talking about, I'm new to all this stuff. Thanks again for your help.
http://im1.shutterfly.com/media/47a2...D720/ry%3D480/

http://im1.shutterfly.com/media/47a2...D720/ry%3D480/

Stand corrected. Look at the 3rd and 2nd from the right columns. The second row or the 3rd column says GT4 meanin 3.73. The 2nd colum has a G80 meanin you have a g80 limited slip diff