Generator & Hot water heater for 1992 Dodge E350

[dodge-ClassB]

I recently purchased a 1992 Dodge E350 Coach House camper van. I need a generator for it. There was originally an Onan generator in the van. There is still an Onan On/Off switch with hours meter inside the van and a cord that has been cut in the area where the generator was originally stored.
What size generator do I need? I think it is a 2.8 but not sure.
Any ideas on Models and what are they?

I also need a Hot Water Heater. It looks like it is under the sink. Looks like it may be difficult to. What size and type?

 

[markopolo-ClassB]

I've only ever heard of 2800 watt Onan generators permanently installed in gas engine Class B's. Some B van owners carry a portable generator.

Do you need it to run the Air Conditioner?

If you can post a photo of the outside cover for the water heater I might be able to tell you what brand it is.

Suburban water heaters are/were quite common in B vans and are typically 6 gallon. Airxcel | Suburban Manufacturing Products They can be pilot light or direct spark ignition (DSI). Some models also have an electric heating element.