I dont know if this is correct or not, but some one told me back when I was a kid ( many years ago!!) that the left side wheels had left hand threads because the turning of the wheels tend to naturally tighten or loosen the wheels according to direction. Personally, I seriously doubt that would happen, but some one thought that any way. Both GM and Chrysler used this arrangement for many years. My first encounter w/ this was on a '49 Pontiac, and I broke three studs before I figured out what was going on. Last time I had that problem. (that was about 1957) I attribute the idea for left hand lug nuts to the same kind of genius that brought us side post batteries, & batteries down inside fenders. Ovmf
