Left hand and right hand threads

Chrysler was using left and right hand wheel studs up until the 1971 model year.  So when removing a wheel  the lug nuts would come off opposite on the two sides of the car and that would tend to create alot of broken wheel studs for people that did not know that.  The thought was that it would help prevent the lug nuts from coming loose from the wheel rotation, which eventually was dropped by manufacturers and no longer used today.  

You can see here what was originally removed from the car two studs that are damaged probably because of this.  Everything is now replaced to a right hand thread to make life easy going forward.