Millermatic 200

A gas shielded Millermatic 200 will give you better welds on sheet metal than a HF flux core set up, hands down. Miller specifically tells you how to set up a 200 for 24 gauge sheet metal, which means you don't even have to believe me. Since the thinest sheet metal you're likely to find on an A-body is 20 gauge, you won't even be at the minimums for the machine.

If you're only welding sheet metal, you won't have to change the wire all the time. If you're not just welding sheet metal, you'll have to change the wire on any welder you get, since you'll have to change it to match what you're welding. This is true of either machine, although the Millermatic 200 will be capable of welding a much larger range of metals.

Guys that spend a lot of time welding might have a smaller unit for sheet metal simply because they don't want to be switching their larger machine over all the time. If you do enough welding, it makes sense to have different welders for different jobs. But again, if you're only welding sheet metal or thin gauge stuff, you won't have to switch it over and it won't matter.

The Miller is 10x the machine the HF unit is. It will last forever, need very little service, and will weld anything from 24 gauge all the way up to and beyond 1/4" steel. Because of its duty cycle, you'll pretty much be able to weld most stuff you encounter all day long without worrying about overheating it.

Maybe you'll never use it enough to find that out. If all you want to do is stick a couple panels together, buy a HF welder, lay down some crappy hot glue gun welds and grind them off.

But, given the choice between a superior, American made Miller welder and a Chinese knock off, I'd buy the Miller.