Well, I diagnosed my squeak on the front left corner of the '99 Expedition (LLS, 5.4, EB, 4x4). It is indeed the lower ball joint... so, I will be replacing the ball joints, wheel bearings while I am there and the front air shocks (with the NAPA version that we just saw on here).
Where have you guys found the best deal on the front wheel bearings?
Hopefully all of this wuill make the truck feel better, and I can actually activate the LLS again. When I fired up the new compressor after installation, there was a leak somewhere, and the pump ran more than it should... this was all in the first two hours or so of driving. It cutout, and I turned the suspension off. Since then it has stayed at the same height - no leaks. I just hope to get it all back together, and finally work as it should.