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
BOSS 8'2" Power V
Hustler X-one 60"
Toro Proline 36" wb w/t-bar controls
JS46 22" walk-behind (wouldn't recommend)
Shindaiwa T254, Echo trimmers, chainsaws, pole hedge trimmer, pole saw, hedge trimmer
Shindaiwa 633 and Husqvarna 130BT blower