Thank you Ernie,

The unit is indeed a HF, 250 amp. Not at the shop now, so I cannot get any
more specific regarding model number.

Got the parts today, and tried it all out. Beadblasted the parts prior to
welding, and kept a stainless wire brush handy. Used a zirc 3/32 tungsten,
1/16 5356 rod, and the new gas lens (NEAT), and fired it up. Still enough
of a newbie to have some "gravitational pull" problems into the puddle, but
the welding went better than expected.

I am welding a solid 3/8 diameter rod 90 degrees to .125 plate. I have
welded the exact same parts in steel, and now in aluminum. The results in
steel had much less weld build-up around the base of the joint. Am I adding
too much filler with aluminum? It does not feel like I am, but the
difference between the amount of weld at the base when comparing the steel
parts, I had made out of aluminum is significant. I suppose a picture is
worth a thousand words so maybe I can post a comparison shot in the dropbox.

Thanks again, Ryan