I think the ad is wrong! 1964 and 1965 A-bodies with 4-speed transmission did not use a slip in shifter. Factory 4-speed cars has a chromed Hurst shifter bolted to the shifting mecanism with two black phophated bolts with 9/16" head. In 1963 there wasn't a 4-speed tranny for A-body cars.
Yes! The case was casted July 22nd, 1963 for 64 cars. Tail stock is casted April 23, 63 or 64. If 63 it can be an early one or if the tail stock was used on 63s as well. Or it might have been changed for a 64 casted one!
Oldvart was right, look up the flywheel as well. You might also check the bearing at the end of the crank. Mine was almost gone and with a new one and some copper grease it became as new.
I have a 65 Dart with 273/4 speed and I would guess that you need a new clutch, disc and the clutch bearing. I just changed that om mine and I got a new car. Any pictures?