All of the above
The holes in the '63 were large and slot-like, and there was the constant rinse on the top. Later models would forego the nice, flat, arched top rack, in favor of a many-tined monstrosity that gave extra space for loading bowls and saucers, but lost forever the nice place to put deeper dishes and mixing bowls/pots/pans.
I had excellent results from my Custom Imperial with the double-wash and double (covered, triggered) dispenser, but I had soft and steamin' hot water. I even got to where I could load pots and pans in the bottom and they'd get clean.
However, the only way eleven-inch plates would fit in that thing would be if we were talking AOL inches. I had some 10" plates, and they would hang up on the top rack, so I had to pull out the bottom rack, pull out the top rack, lift up the top rack, stand up the plates, let the top rack drop back down, push both back into the dishwasher, and voila.
Needless (needle-less?) to say, that lost its charm after a while.