What type of transfer case fluid does the 2005 chevy 2500hd use?

The 2005 Chevrolet Silverado 2500HD's transfer case fluid depends on which type of transfer case Your 2500HD is fitted with. If You have a manual transfer case (or all wheel drive and an automatic transfer case), You'll need to use DEXRON-III transmission fluid, approved for H-specification usage. The final part is important, since not all DEXRON-III fluids meet this heightened specification; using inferior fluid can cause long term damage, and I don't need to tell You that's no bueno. On the other hand, if You have an automatic transfer with two-wheel drive, You'll need to use Auto-Trak II fluid in the transfer case. This is a bit different, so it's important to not get mixed up. Check Your documentation, and be certain of what You've got before You change or refill.