I did this upgrade. Twice. My original MH had a Parallax 7345 and I upgraded to a Progressive Dynamics PD4655V for $200. When I traded that off, the new trailer I bought came with a Parallax 8355. I did the same upgrade for the same price.
PD4655V at
http://www.bestconverter.com/ They also have the
PD4645V.
I did my own labor. If you are handy, it is not hard.
UNPLUG FROM SHORE POWER AND DISCONNECT THE BATTERY. Unscrew breaker box from wall and slide out, removing cover. Disconnect 2 wires from breaker box, HOT and NEUTRAL. Disconnect 2 wires from 12v circuit board, HOT and GROUND. Slide out the old converter charger and slide in the new one. Connect 2 wires to the 12v circuit board, HOT and GROUND. Connect 3 wires to the breaker box, HOT, NEUTRAL and GROUND.
Now, there is one twist. You need the charge wizard. The kit comes with a new 12v circuit board with the charge wizard controller built in. I suggest you replace the existing board with the new one during this process. If you really don't want to do this, you can buy the optional pendant instead for $15 (that is a $10 discount from his usual price). Replacing the 12v circuit board requires you to move 2 BIG wires (from the battery), HOT and GROUND, and also to move all of the 12v circuit wires. That is it.