I have drove the same 78 R Model Mack for the past 28 years, the only thing I have had longer is my wife. Me and my MACK haul coal here in SW VA. Recently replaced frame rails and we are back on the job. Powered by a E7 350, 2180 transmission, T200 rears, none of this is original! Glad to have found this website and look forward to getting to know you. Will send pics later. Rod