Bumping this thread. I may still spring for the Dynatrac ball joints but here's some more info.
The cost of Moog ball joints on
http://www.moog-suspension-parts.com/ is slightly less than half than the Dynatracs at ~$250. Amazon or Rock Auto is much cheaper. The reputation and apparent quality of Moog has gone downhill in recent years.
NAPA ball joints are apparently made by Spicer (DANA). My NAPA parts guy had a hard time cross-referencing the part numbers using the Spicer #. Go figure? The only difference between NAPA and Spicer may be just that the Napa is greaseable. It would be interesting to know if it is made for NAPA to higher spec.
Motocraft, like Spicer, are sealed and not greaseable.
XRF gets rave reviews on the truck forums but are made in Taiwan. However, you can pick up the set for $125 from
http://www.thetireclub.com/content.wws? ... _KITS.html
The XRF are probably the best deal if they are indeed a premium ball joint. I don't know the pricing on the NAPA ball joints just yet.