I own an 06 GMC 2500 with the 6.0 and I can tell you that you won't get what your asking on eBay. My auction ended at $8,900, you would top out at $10,000 because you have less miles. Your asking a diesel price for a gas truck.
There is an Old Blue Chair for each and every one of us, we just have to find it.
2006 GMC Sierra 2500hd crew cab with 6.0 gas
Hustler X-one 60"
Toro Proline 36" wb w/t-bar controls
JS46 22" walk-behind $500 piece of $h!t, don't buy one
Shindaiwa T254, Echo trimmers, chainsaws, pole hedge trimmer, pole saw, hedge trimmer
Shindaiwa 633 and Husqvarna 130BT blower