The fuel gauge in my 04 2500HD Sierra has never been right since the day I bought it. Had the truck serviced in august and the dealer claims that they changed the sending unit, but I was still unwilling to believe the gauge was reading correctly and my suspisions were confirmed after the next fill. It's like beating a dead horse dealing with the dealer, so I just live with it. When the indicator on the gauge reads 1/2 full I know there is a 1/4 tank left. Any advice? I could use some.