I had a 2003 GMC Sierra 2500 HD Duramax Diesel 6.6 liter engine, with 105,000 repaired at Royal GMC in Tucson AZ while I was RVing in the Tucson area for a month. Requested repair was to replace four fuel injectors (#1,3,5, and 7), due to white smoke when idling and accelerating. I had no other prob ...