Rarely will I use TIG for Body work, that said if I have a component that I want fastened to the body with a small weld line I use TIG as I have better control over the heat , fusion and filler material being added to the puddle. All of the Exhaust work is done with TIG, but can be done with MIG, no flux core. A lot depends on the machine and how it lays the bead. The Cebora I can weld in a hole by just going around in circles, it is a constant voltage machine. I have done some 1/8" aluminum with MIG as well using straight Argon, high wire speed and lower current.
TonyK.
Grimsby Ontario Canada.