Metal filler?

[Adam Smith]

I would spackle those corrosion pits with a steel-filled epoxy, like J-B Weld or Devcon "Plastic Steel" or the Loctite equivalent. You just mix up the epoxy and spread it over the pits with a putty knife. After it cures overnight, you can sand it smooth and then prime and paint.

J-B Weld is pretty much the same as the Plastic Steel, and you can get it at auto parts stores. For the other Devcon or Loctite products like the aluminum or bronze filled epoxies, you have to go through Grainger or McMaster Carr.

Bondo is a polyester resin, cheap, but nowhere near as strong as the metal epoxies.

[JasonC]

I went ahead and Bondo'd the housing. All I really wanted it for was aesthetic purposes, as well as some sort of filler to keep rain from puddling up in the divots and re-rusting the bar. Structurally, the bar is very sound. Its been sandblasted again and primed (pix soon) and it looks like the Bondo did an excellent job, as it has completely filled in the large dent, as well has the infinite small/medium corrosion pits and several small holes. I was very happy with the outcome. I'll try the metal epoxies next time.