The distributor diagrams from Ford does not show a gasket under the Vacuum adjusting nut nor a washer in front of the rotor. There is no part number for either. Thus, is this just an improvement on Henry's design?
There typically is no gasket under the nut.
However when we rebuild them we use a gasket that we get from our injector business (its a IAC valve gasket ) or a oring to seal this area.
After some vacuum testing i really dont feel a gasket is needed as the fit is fairly tight ( some just use a heavy grease on the threads) as the overall volume of the vacuum signal is fairly large and a slight loss wont be seen as a problem...
Most dont need a washer under the rotor top as well.
Although some rebuilders after replacing the outer bushing add a washer or small shim to re-establish the end play clearance ( back and forth).
I suggest peening the rotor shaft lower end ( to remove all play in the rotor) and then adjusting end play by prying the rotor up and down with a screw driver after assembly.
Seems to work for us....