I have a 2005 Gmc topkick 4500, with a Duromax engine. The vin code called for a LLY engine, bought a used engine, placed in truck, will not run right, like its in Limp mode. The truck is a Bucket Truck, I am being told the truck was not a complete vehicle from factory but a cab chassis. So the Engine was not A LLY but the one before that. So now I have a LLY engine in it. What would it take to make the LLY run correct with the exsisting computer???? Any advice would be greatly appreciated.