Started on the vinegar tank soak three days ago. After three days, I had to drain the vinegar back into a five gallon bucket due to losing the seal on the petcock. Luckily I was smart enough to place the tank atop of the bucket and was able to recover the vinegar for a second round of soaking. While thinking of a better method to secure the petcock hole, I flushed her out with my garden hose about three times and am quite pleased with the results thus far. For round two (another three days) of my vinegar soak, I cut a piece of bicycle tube and clamped it around the petcock hole with a hose clamp to ensure the integrity of the seal.
Note: Flash rusting was readily apparent and spread like cancer after only seven minutes (yes I timed it) after flushing the tank of water. Ensure that you have your acetone, ATF, Seafoam, two-cycle oil, WD, or whatever flash preventer you plan on using "at the ready" when you are done with the vinegar regiment. As for me, I intend on using ATF given the overwhelming positive press it has been given on this subject. Alas, I am going with the concensus.
P.S. I you have as much $hit coming out of the tank depicted in 750K's pictures above, you need to line your tank. Do not think " I will be fine". Fine, my friend....is only a matter of time. One does not need gray hair to be a wise man.