Dennis,
The 50 amp service is probably 50 amps on each of the two 120 volt legs of a 240 volt service. Another way that trailers got a 50 amp service was to have a 30 amp and a 20 amp 120 volt service. Look at the main circuit breaker in your unit. If it is ganged (connected) together, and each breaker says 50 A, then it's the 240 volt setup.
The 240 volt plug is a 14-50R with four prongs where it plugs into the CG pedestal and a big twist-lock that plugs into the unit.
Go to this site
http://www.myrv.us/Pgs/RV/50amp.htm for a better description and some pictures that might help explain it better.
Bob