I purchased my U. S. Gear O/D and installation from Camper's World in Mesa, AZ. I don't see them advertised in their catalog anymore, just Gear Vendors. I have had great luck with the USG unit. I tow a fifth wheel, haul a camper and/or tow a boat. That with the O/D unit and 3:55 gears. I have 80k+ on the unit. As for a dealer, I would agree that going to the manufacturer for a list would get your information.