[real550A]

John- I used the electrolisys method on the inside of my '72 tank, and it really did a fantastic job.
In a nutshell:
Fill tank with clean water, add 1 tablespoon Lye per gallon.
Suspend a stainless steel rod (electrode) into the water. (I hung it from a board through the sender opening.)
Make sure electrode is not touching metal tank!
Attach + cable of battery charger to electrode, and neg. cable to metal tank. (filler neck works good).
Do this in a well ventilated area, as the byproduct of this method is Hydrogen!
My tank took 48 hours @2 amps, and came out looking new and grey
inside. It was really bad after sitting over 18 years.
I then flushed it out with a pressure washer, and chunks of rust went all over, but the tank looks mint inside now.