I replaced both of the anode rods in my 11 year old 50 gallon Bock water heater in January 2016. Bock recommends pipe dope not Teflon tape so the rods can be sacrificial instead of the tank.
After conferring with Bock, I used an impact wrench to remove the rods along with two wrenches and a band saw to cut the original 36" magnesium rods. The inside threads had been stripped by the service technician while trying to muscle them out. Original rods are cemented so an impact wrench is safer (I have a 700 ft-lb Milwaukee Fuel). I then used two wrenches to hold the rods in place while cutting them in half for removal so the bottom half does not fall into the tank.
I also removed any rust and painted the bottom with Rustoleum high-heat paint over rusty metal primer. I had to replace the linked anode rods because of only 18" of clearance.
Jan 2018, I just had a clean out and my 1989 Peerless with 2008 Beckett and my 2004 Bock with 1989 Bock/Wayne head are just fine. The hardest part was finding the hex head socket and the tapered tapper to restore the threads. There have been no leaks with the pipe dope.