Sorry I forgot to mention that if your tank has a drain plug just take it to as RV dealer so you can check thread size and they do make anodes in several lengths just replace the plug with the anode and use teflon tape for install. I have seen some tanks where they suggest you use the blowdown valve for draining the tank but this only causes leaking blowdown valves after a couple of times. Then you are replacing a valve at a higher cost.