The parts were all factory Nissan, hence my confusion. However, I seemed to have solved the problem by using a .005" shim between the lower bearing and the kingpin. Apparently Nissan changed from NTN (factory bearing) to NSK (new bearing) at some point; the NSK bearing has slightly different chamfering on the shoulders, and that caused the play. At least, that is the only explanation I can come up with. Looking back on the whole situation, I should have just bought new links and called it done. Thanks for you input :)