Yup, 78-97 are D60's
78-79 are King Pin and preferred by most and seem to be the most expensive to buy, rebuild, etc. They are also the hardest to find.
80-97 are mostly ball joint D60's, still hard to find, not as expensive to buy, or re-build, and it is certainly easier to service ball joints than king pins, but not as strong, and the high steer options arent as plentifull since most high steer arms out there go over the cone on the king pins.
These were all 8 on 6.5 except for some very few 7 lug bastard versions out of Canada.
98 Ford didnt make a F350.
99-02 most F350's had D50's, Unit bearings, not nearly as strong, very few locker choices and r&p selections, aka garbage.
03-current most had D60's, still the shitty unit bearings, but hey its a D60 so it cant be all that bad. IT IS! Fortunatly Dynatrac makes a conversion kit for it so you can run the very useful and stronger/conventional style sheel bearings, and Warn Premium hubs.
99-current are all 8 on 170mm
Hope this helps.