Hi all - just a quick update - I got the converter installed.
It was pretty straightforward - there were just a couple of things that needed done.
I had to add a piece of wood since the old case would have limited the fan/airflow of the new converter.
http://eanubis.net/2004TrailBay/Converter_WoodAdded.jpg
The new converter has the wires on the opposite side compared to the old one. It took some creative routing to get the red and white wires to connect, but they do leave them longer than usual - so that was good.
I also added a loop and heatshrink tubing to the end of the red wire to fit on the old connector properly.
http://eanubis.net/2004TrailBay/Converter_Installed.jpg
The new 55 AMP converter states that it needs to be connected to a 30AMP breaker, when the old converter (also 55AMP) was connected to a 20AMP breaker - as the tag on the wire stated.
I don't have a 30 AMP breaker available as that breaker is being used to run the power to the panel, so I connected it back to the 20AMP breaker. All of the interior lighting has been switched to LED, and we're not charging any batteries, so I doubt that it will exceed 20AMPS at any point.