Just measured the original and the new uppers. The difference between the two is about 4 thousandths, and that was with the new ball joint still cold from being in the freezer. I pressed them in until the threads just got to the top of the control arm and then hit them with the impact. It did not take much force to press them in to the threads.

The big difference between the two is the old ones have a tapered front end (the taper ending about a quarter inch from the front end), while the new ones do not. This makes the original easier to get started into the hole.