Mobile Temp G601 water heater

The burner is missing.

I'm guessing this tank cracked from freezing and the PO may not have known that. They start to leak like crazy when pressure is applied. Also, somebody added a new drain to the tank, a little late, IMO.

In any case, it's not worth messing with.

Your answer depends on how you intend to camp.  I like the idea of the combination unit, but in the long run, if you are camping more where you don't have the amperage to run an electric unit, then the propane-only is less expense and easier installation.  Also the new units are quite a lot more efficient than the old ones.

Personally I opted to stay as close to original as possible, and I am finding that the simpler design of the original is quite workable.  I installed the propane-only with the pilot, which is really the simplest mechanically speaking.

 I do not know if there is a direct replacement for that particular heater, but the cabinet can be refitted to a modern unit. Just make suer you are fitting your utilities to fit your choice, i.e. wiring  and plumbing, to fit in your replacement unit.

Usually, the small amount of water doesn't crack the tank but a full tank will not like a hard freeze... A bypass kit is handy and you can add a little RV antifreeze when winterizing.

I agree with Ten that simpler is better; the old pilot models last a long time and no electronics (circuit boards) to go bad. You can always add a "Lightning Rod" for an easy electric option. At least that's what they were called in the good ol' days.

I doubt there's hope for your water heater. First, test it under pressure for a cracked tank. Put water to the system and you'll see the water. Sometimes it gushes, sometimes seeps.

Parts are pretty much unavailable.

We’ve used our tankless heater for more than 10 years now and are perfectly satisfied. It runs well from both city water or the storage tank. A battery signals the gas to come on when it senses water pressure. One does have to adjust the temp a bit to accommodate particularly cold water for late autumn or early spring camping, but that’s easily done with the controls on the unit.

We have had two leaks, probably from not draining the unit completely in winter, but my hubby fixed the problem easily. You don’t say whether you have a bathroom or not, so placement may be an issue. We reinforced the wall in the closet (Compacts had a huge closet that turns nicely into a wet room8 and hung it on the front wall behind the porta potty.

Good luck!