Hey guys I am trying to find out how big the fuel tank is on my 2005 sierra 2500hd crew cab. Anybody know how many gallons or litres it will hold? What sort of fuel economy are you guys getting with stock trucks? I always heard that you get almost double the miles or kilometers on a tank of deisel than you do with a similiar gas truck which is part of the reason I switched to a deisel truck, however after owning this truck for two weeks now I am a bit disapointed in the fuel economy so far. I have used up 3/4 of a tank and am only at 340 kilometers and the range computer says I have about 108km left. That is a tiny improvement over my 2000 gmc seirra 2wd with the 4.8 v8. I have friends with fords and dodge deisels saying they get 600 to 800 km on the same amount of fuel.