Here we have a used engine bay wiring harness removed from a 2004 GMC 2500hd with the 6.6 Duramax, 6sp manual transmission and manual shift transfer case. This is the harness that runs around the engine, NOT the one 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.