> The fill plug is stripped out so badly by the P.O. that my 17mm allen
> wrench is way too small.

You need a TIG welder.  Weld an old socket to the stripped drain plug and
wrench on that instead.  I've done it before, takes 5 minutes.
MIG welder won't work, too sloppy and imprecise.
If you lived near me, I would do it for you.

Good luck
Gary Lee
http://www.telusplanet.net/public/gary2a/rack/vanagonrack.htm