I have a chance to look at several older Miller welders that a local company is going to sell. I want to get into TIG welding but can't seem to find what model numbers allow what kind of welding process. The machines I'm asking about are

Miller Goldstar 300SS

Miller SR-200

Maxatron 450

These machines come with no cabling or the like, just the welder. In short can I TIG weld with any of the above welders. All are in pretty good shape, but I don't want to look like a complete idiot when I go to put money down on them. Any help would be welcomed.