I think that they are feeding you some BS about the gas eating away at the contacts. I think it is more likely that they are useing the wrong materials for their sending units. Cuz if it were the gas then why isn't it eating other things up on its way to and through the engine??? Oh and further proof that it is all GM is the fact that they have had this problem for a while across the entire truck line. Hell even my Blazer's sending unit hasn't worked in two years.