It is not expensive.
Atwood water heater tank cracked.
New seal rings gaskets kit available atwood 96010 should come with new tank if that is way you go.
I d replace the water heater.
All atwood tanks are aluminum and can be welded if cracked leaking hopefully with tank still attached to front of water heater drawn pan etc if tank needs to be separated from drawn pan etc then the seal rings around combustion chamber and exhaust port have to be cut off t p relief valve removed old version uses 1 2 style.
The tanks are so thin that welding a crack isn t likely to succeed.
One of the primary issues with older water heaters is the buildup of sediment caused by natural minerals in the water.
If you have an atwood and it is functional other than the leak get it repaired.
Most water heaters rely on a simple set of heating elements piping and controls in order to operate.
The pic in your signature suggests that there are more than 2 of you so i d upgrade to a 10 gallon if there was room for it to fit.
Trailer life and motorhome magazines bob livingston and bill gehr show you how to replace the inner tank of a leaky atwood rv water heater.