The issue is ball joint strength. The ball joint can shear where the taper ends just before the ball. Ma Mopar increased the size of this ball joint to reduce the chance of failure.
Now, if driven like a grandma, straight lines, only to icecream shows on the skinny stock bias plys with 10" drum brakes....... That would not be an issue.
But if driven more aggressively with a larger tire footprint and a heavier sway bar (and more engine - - warmed over 360)....and the modern disk brakes; the chance for the smaller ball joint failure increases!
