Welcome Bowcat 66.  I am still on my original anode, it is now 12+ years old and in pretty good condition.  It has only seen well water, I believe if city/muni water is used the life of the anode is greatly reduced due to all the chemicals added to that water.

Your owners manual is . . . . .  HERE!  Ask away and someone will most likely be able to help.  I have been helped many times by the 'expert' podders who have a lot of experience under their belt.

There are magnesium anode rods which are more chemically active and will sacrifice themselves more quickly to protect the steel in the tank. The aluminum ones last longer, but since they are not as chemically active, they don't provide quite the same level of protection. Unless you are having to replace them every year, sticking with the magnesium rods is probably best.

(Aluminum vs Magnesium anode rods) To be honest, one anode rod is better for hard water, and the other is better for soft water. When you are camping in hard water areas, the aluminum anode rod is the best one to have inside your water tank. It is less reactive than magnesium and also, and aluminum is better for those areas with a lot of sulfur in the water supply. On the other hand, magnesium is very reactive and removes corrosive materials faster than aluminum anode rods can. But that reactive state is better in soft water regions of the country. The aluminum anode rod cannot work fast enough in soft water making it the inferior choice for those water regions. It turns out that the popularity of magnesium, despite what some owners have said, makes it possible to be the least expensive of the two. That price difference will depend on the store you buy your anode rods at. The problem with magnesium is that it comes with a shorter lifespan than the aluminum model.