Here we have a good used engine wiring harness removed from a 2004 GMC 2500hd with the 6.6 Duramax, automatic transmission and electric shift transfer case. This is the harness that sits right on the engine and plugs into the injectors. This is used, but removed from a running and driving truck, may have cosmetic deficiencies or cracked plug ends from age but will work fine in your truck. This will fit 04-05 trucks with the LLY engine ONLY but please compare it to your existing harness plugs to ensure its the one you need, these are non returnable. if you need any parts just inquire.