looked bumpy. I took it out and it is a aluminum version, How do I
clean it? lime away and some scraping? My labor is cheaper that
buying new parts or heaters.

Replace it.

Bob

so the OP got a used tank hopefully for free...........

by the time he replaces the anode, replaces the elements and cleans
the sludge out of the tank.....

Has he wondered where that sludge came from? Almost certinally from
the inside of the tank which is nearly rotted out

Now he has a old tank, thats less efficent than a new tank with high
efficency foam.

So his tank has cost probably cost nearly as much as a brand new cheap
short warranty tank