I have a 95 2wd dually w/5 speed stick w/3.55. Pulling a 32ft tri-axle I get 12-13 at 65mph. It has a #10 cam plate & 4" exhaust. I put 285 tires on the rear to lower the engine speed ,it didn't help much. We've had this truck since new. When it was stock pulling a 28ft trailer milage was about the same. Sure would like to see milage like Mr P.
Doug