There are two major articles on this. One, "Disk-o-tech" was written by Richard Ehrenberg. It talks about "ball joint overangling" and bump steer and toe changes with using the B/R/F/M/J spindles. All of it was speculation on his part, he never actually checked or published the data that supported what he was saying. Basically, he published a bunch of nonsense and stands by it to this day. The article is useful because it lists a bunch of part numbers and different ways to ID the factory parts, but almost everything he said about the geometry changes was either total BS or wildly exaggerated.
The second article was written by Bill Reilly. Unlike the Ehrenberg article, it actually compared all the suspension geometry between a 73-76 A body spindle and the 73+ B/R/F/M/J spindles. It includes the published data, which shows that while there is a very minor increase in toe changes (not a big change at all), there is also a very beneficial change in the camber gain curve using the later spindles. So much so that it's likely that the camber gain improvement outweighs the very small change in toe. You can argue back and forth, but for a handling car running wider front tires the camber gain would be a much more noticeable effect than any increase in the toe change. More than likely, the average driver wouldn't notice either on a regular old street car. And the "ball joint overangling" thing is total horsecrap.
This is the second article, it shows the data, explains what was done to get it, and what the changes actually mean. I'm not linking Ehrenberg's article, because other than the ID information it's just Ehrenberg making crap up and the BS outweighs the good information.
Swapping Disc-Brake Spindles - Mopar Muscle Magazine - Hot Rod
