What's the Best Weld for Cracks and Patches?

[Tom Wesenberg]

I bought my Lincoln SP-125 MIG welder about 20 years ago with the idea to use it for doing body repairs on my Model A's, such as rust patches, or fender crack repair. A few years ago either Flop, Brent, or Kevin mentioned that MIG produces a hard weld. I used my MIG to repair a cast iron generator pulley with a piece missing. I thought I would file the weld to shape, but the file wouldn't even scratch the weld, so I had to use my Dremel with a grinding wheel. That's when I found out just how hard the MIG weld is.

I'm thinking such a hard weld wouldn't be good for repairing a fender crack because it would probably be so hard it would crack again quite easily. When I repaired the missing metal in the log splitter cover I decided to gas weld it, and that worked fine. So, for Model A fender patch work or crack repair, is TIG or is gas welding the preferred way to go? Or are they equal in weld quality and durability? Thanks