Thanks for writing back. I gave it some thought. The “better” tank looks to me like it is a 5 year old tank, but the more beat up one looks like it is 15, even though both have the same install date of 2008. If 2 tanks are in series, does the first one (cold water input) take a lot more abuse than the second one which receives warm water input? The temp on the first (cold water input) tank was always set a few notches lower than the second to try to equalize wear. Of course, the tenant may have reset the first tank to mega hot for some reason and hid it from me, who knows. Anyhow, I suspect the beat up tank will not make it another 4 or 5 years. We will be selling in about 4 or 5 years, so if I replace the beat up, rusting tank now the new tank will catch up with the existing tank at right about the time we sell, and both will be in similar condition, assuming the current trend holds. I’m calling the plumber in the morning for a new water heater, the existing good tank gets a new anode and T&P valve. I can do the house surgery to make an opening, the plumber can carry the %&&@*ing tank into the attic and haul the old one out. The association won’t allow the tanks outside and the garage is too short to put the tanks there, so no choice. Too bad, putting the tanks outside the garage would cut the length of the pipes to the water heaters from about 60′ round trip to 15′ round trip, since the PEX header is in the garage.