What is the 2006 chevy 2500hd rear differential fluid capacity?

Depending on Your specific rear differential in the 2006 Chevrolet Silverado 2500HD, You'll use the same type of gear oil (75W-90), but varying capacities. The 06 2500HD was available with a 11.5 RG rear differential, a 9.25 RG rear differential, a 9.75 RG rear differential, a 10.5 RG rear differential, a 9.5 RG rear differential, or an 8.6 RG rear differential. Depending on what Your model is running, You'll use somewhere between 2.5 quarts (for the smallest 8.6 RG) and up to 3.27 quarts (for the largest 11.5 RG). Of course, this is a relatively small range; it's much easier to know what You're getting into once You begin the fluid change, so just be sure You've correctly identified Your specific truck's rear differential before beginning.