Paula -
Can you tell us the make and model of the water heater? The one used today has both an electric element and an anode rod, and they are not directly interchangeable (different size insert plugs). It sounds like yours had only an anode rod, and a previous owner took that out and substituted an electric heating element. Note that no anode rod means no protection of the tank from corrosion.
Have you gone on-line to the web site for the manufacturer of the water heater? The most reliable information is always available direct from the manufacturer.
Again in more modern trailers, there is no need to pull the anode rod to drain the water heater. It can be drained from the valves under the trailer - two just in front of the street-side tire, and two behind the waste water drains. This is shown in the plumbing system diagram here
http://www.trailmanorowners.com/foru...&pictureid=435
I don't know if it is directly applicable to your trailer.
If your trailer came with a blue binder book, do you have it?
Bill