Careful
I'm currently replacing my head tank on my '80 H-37C. Be careful which tank you pick. Ronco's B223 will not fit, according to Morrie. It is too tight of a fit. Be aware of the narrowness of the door openings - I believe it is 20 or 22".My solution has been to cut off the top of the shower seat. I was able to remove the old tank, intact. By enlarging the tank (5" taller, 8" wider at the aft end) it should end up in the 25 to 30 gallon range. The shower will still be intact, but the seat will be deeper and taller. If you would be interested in doing the same style tank replacement it would likely be wise to go in on a new mold together at Ronco. Let me know if you'd be interested. I'll post some pictures in a week's time.