I had a 383 a-body bar break in my 64 dart. It had a worn "notch" about 0.030" deep, from a collector flange. It was a smooth "notch", not a sharp gouge. My friend was trailering it to a race in Spokane for me. He chain-bindered it down, and then added air to the tires. I think he overloaded the bars. He hit a bad pothole at the strip entrance and the bar just broke. I think it was a pretty unique situation, so I don't think it is all that likely to happen. That said, I'm glad it failed on a trailer, and not in the traps.
I don't see why anyone should resort to vise-grips to remove a bar. All you ever have to do is back down the adjuster, remove rear retaining wire-clip, remove LCA pivot nut, and pry between front of LCA and rear of crossmember, with a crowbar or even a oem lug wrench.
