I need to find a manual for a 2003 GMC C4500 4x2 with the Duramax Diesel. My father has one with a dump bed that he uses for his business and the dealer he got it from sells mainly work trucks already outfitted with work bodies and what I think what happened is when the dealer sent the truck to be outfitted for the body either the body builders or the dealer lost the manual and the need has come up several times for one and nothing can really be done.