I am restoring a 1973 F-350 Camper Special with a new 460 engine and 3.73 gears and C-6 transmission. I plan to use it for towing a 5th wheel or Travel trailer. The charts I have been able to find just don't go back that far. But I am assuming that I can tow just about anything as John says. But is there a formula to use. I think the only number I know is the GVR which is 10000 lbs.