I did think of what it might be. When I reassembled the knuckles I greased them so I could make sure to get a lot in there and the kingpin bushings were tight since they were brand new. When I checked for end play the tight bushings and packed in grease could have made it seem like there was none, but as soon as the truck is on the ground driving again there goes the axle seals again. There's little pucks on top of the top kingpin bushings that control the end play. The military did have kits available with different thicknesses to get the correct fit. I'll tear it down again(approaching pit crew speeds) and check. If that's the problem I'll have to get some thicker pucks or mill down the top kingpin plate. I also found a place that came up with a new design for the seal and retainer, so I'll check into that, it might be worth the money.