I would not go with a Parallex 7300 series, As I posted above it is a single stage converter the output voltage never changes, Thus it either over charges or never fully charges the battery.
NOW: you may be able to replace the electronics on you ATTWOOD.
Or, Well there are several that are that size or so close one would never notice.
One thing you can do... If the new unit is SMALLER. a sheet of metal, cut the proper size hole in it and paste it over the original opening.. Done right it looks factory.
