The hardened 4th clutch shaft should be mandatory regardless of what the old one looks like, it WILL go bad at some point which leaves you with no 4th gear. The other hardparts all need to be inspected before replacement as there is no sense in wasting money on parts you dont need. As far as the converter you should replace it with the same code that is on the original converter unless you want a higher stall speed. They dont rate stock converters as you would expect, or like what aftermarket companies advertise them to be. Mix N Matching original torque converters is trial and error unless you know of one that will give you a desired stall speed but I always replace them with the exact same code unless you want a higher stall speed and every car will respond different so it is hard to say an exact number.
