RVers, I took some time and put together list of several different 75 Amp power converters to see if I could help you decide what you might want to buy.
You can think of a power converter as a AC to DC power converter. They do more, but this is the simplest essence of what converters do. Another, more inaccurate way of viewing this is a 110V to 12V converter. The accurate way of saying that would be 110VAC to 12 VDC.
Learn more about RV power with my RV electrical system tutorial.
I replaced a deck mount converter in my Open Range 399BHS.
75 Amp RV Power Converter Manufacturers (so far in my list):
These are in no way an exhaustive list. Also a manufacturer might not make a 75Amp converter and might instead make an 80Amp.
Question: How do you know how many Amps you need? You first count all of your 921 lights and just use 1 Amp for each bulb. That can add up really fast. I would allow a few Amps to charge the battery. I think you can ignore the igniters for LP gas stuff, but for the water pump that would take several Amps (read the literature) for somewhat extended periods of time. If you can afford to buy a bigger (more Amps) converter and you have the space for it, this seems like a no-brainer to me.
You can try the RV Power Converter Size Calculator.
To find a bigger selection of power converters than “just 75 Amp” converters, check out the Power Converter Database Selection.