If they did not upgrade the wire from the 50A plug to the panel to #6, it's not up to code, a safety hazard, and a fire danger from overheating undersized wire, and in the event of an electrical fire, your insurance is probably not going to cover you. The wiring from the panel on is OK as the loads on those circuits is not going to change. It would pay to check it out.
2013 F250 XLT
I now have a Keystone Outback, but I try to help when I can.
Bitter Gun Owner