In my Challenger after mods to the motor in the summer of 1971 drove over the Dana. Challenger had very little miles on it maybe 400. From there it had a 1970 Dana in the car. In 1971 Chrysler for some reason decided to change a lot of things for the worst. Danas, Four Speeds were two of the Changes. I wonder if they saved any money doing this because I bet warranty took care of the cost savings if any.