I have a 07 3500 srw with 123,000miles on it. The motor is a 5. 9. I run completely stock, and I work this truck pretty hard. . lots of mid weight towing(10,000 lbs) not on the highway. I lost my head gasket/injector harness at 75,000 miles, my #1 injector failed at 110,000 miles, and now my...