The Ackerman was correct when I located the front and rear axles a few years ago following some rear suspension work, but I'll confirm that. The steering is a side-mounted Mustang box connected via drag link to normally-mounted spindles. I did find that the toe had drifted out (by a lot) two summers ago - so bad that it caused shimmy. That could have caused the wear problem, but that doesn't explain wear on the first few sets of tires when I know that the toe was correct. Of course, I'm only "really sure" that the toe was correct back then, but maybe not.

From your replies, it sounds like the problem is toe and not camber. The guy at Speedway also suggested toe-in, but I wanted to hear from the folks here.