In our '85 Regal, we have a 6 gallon Atwood gas water heater. It has an anode rod that needs to be replaced. The existing anode rod has no drain plug in the end, so when you want to drain the hot water tank, you have to take the entire anode rod out. I've put a mic on the NPT threads and they appear to be 3/4". The rod itself measures 4 1/2", at least that's what's left of it. Problem is that the only anode rods for Atwood heaters are 1/2" NPT and 4 1/2"long, either with or without the drain valve in the end of the anode. Suburban heaters have 9 1/2" long anode rods and 3/4" NPT threads. To further complicate the picture, Atwood says they do not, have never, used anode rods. Yet I have one of their heaters that clearly has one in it and it does appears to have been a part of the original set up. Of course the person I talked to at Atwood wasn't even born when the heater was made, and is absolutely sure Atwood never has used anode rods. NEVER,NEVER,NEVER!!! It's amazing that young people think that if it isn't on their computer it never has existed in history. Please help?
Jim

If Atwood has never, never, never used anodes, you may have an after market addition. I haven't checked recently, but at one time they were available.

As I recall, anodes are typically one with the drain plug, so taking the whole thing out is par for the course. If your old anode still has solid metal, it will continue to do its job, though scraping off some scale wouldn't hurt. If it crumbles away when you try to scrape it, you need a new one, or in the alternative forget about it. If your HWH is a dark ages model, it may well soon be due for replacement, anyway.

BTW, electric heating elements bear a strong resemblance to anodes. If it has a wire attached, or a place to attach one, it ain't no anode.

If the threads and the plug match your heater, & the longer Suburban anode doesn't bottom on the other end of the tank, it should work. Generally speaking, more is better, anyway, though not always.

I said "if" the threads & the plug match. On house type electric HWH, you find matching threads, but the plugs are not always the same, & one kind won't seat in the well for the other. This might apply to RV appliances as well.

Atwood never did have the rods but suburban did. There were aftermarket rods for the Atwood and I still believe they are available. And you are right, they did screw into the drain hole.