I MIG welded mine, don't bother with buying a boxing kit. Just get a small piece of plate steel (1/8th inch thick?) and cut it about 1 1/4" wide (if I remember right) cut it a little smaller than you think you'll need (it may have been 1 1/16th"), otherwise, it won't sit flat. Use a jig-saw with a good metal cutting blade, keep it cooled off so it won't dull in the first inch that you cut.
I managed to do it, and I've never welded in my life, I was impressed with how well it turned out. I'd reccomend using TONS of wet rags to keep it cool so it won't warp. You really should replace the bushings when you're done, chances are, they'll get hotter than they should. Don't forget to paint them when you're done.
