Nuts in tank : )

[GeeP]

Corks up to 2.5" or so are available at many hardware stores.  (For the filler neck)

Agreed on the blockoff plate.  Except, I would use Aluminum.  Much easier to work with hand tools.  A small hobby piece can be found at Lowe's, or you can look for a suitable drop at the local metals supply (if you have one).  Make a small gasket from some 1/16 cork from NAPA.

[shiznizbiz]

You could always train a mouse to use sand paper.  that would be the greatest ever.

[The Buddha]

For the fule petcock I use inner tube and get the pickup plastic filter tube pulled out and both it back in with inner tube in the middle.
The Cap - yes rubber stopper is OK.
You actually do acid, then drain it, water from a garden hose, then baking soda with boiling water - 1 gal is plenty and you only use a couple spoons of soda cos the garden hose should get the acid out, and then follow with very hot water. So, acid, garden hose, baking soda and boiling water, and then boiling water. The tank has to be very hot, and when you top the last of the water out, somehow dunk a towel or other absorbing thing in it, and soak up the water and get it dry. Then sit in front of a very hot space heater. Without tank being hot when you get to the last of the water ... you dont have a prayer. The GS tank holds in pretty much 1-1.5 pints, plenty to bury your POR 15 into a useless lump at the bottom of the tank.
Cool.
Buddha.

[loki7714]

http://www.por15.com/prodinfo.asp?grp=1&dept=1

[5thAve]

Loki,  I'm going to do this in the next couple weeks, depending on weather.  How's it going with you? Have you done this job yet?  Please share your advice here.

Muriatic acid is an old name for hydrochloric acid.  Available at hardware stores and pool-supply stores.  It is used to lower pH in pools.

[loki7714]

Buy as much alcohol as possible! 90%
No water without baking soda in it shound touch the tank after the acid! Learn fro my mistakes...

[5thAve]

OK.  (But you make it sound exciting!)   

[loki7714]

Woops lol meant isopropyl alcohol Get a lot... and have everything together before you start b/c after you pour in the acid it can get hectic