Spoke with the former owner (2nd owner), and he said that the air suspension was replaced with "heavy duty" springs by the first owner. He didn't know the brand or model number, but that they did sag at all even with his boat and trailer attached to the back.
My shock bushings are wallered out (that's the technical term... I think) and they don't seem to control the motion of the vehicle very well. So I'm going to bite the bullet and buy Bilstein 5100s (p/n 24-197649)for the front and probably Rancho XLs (p/n RS999306) for the rear.
I've been scouring the internet for drop-in rear shocks for Armada's with deleted air-suspension and a small lift (which I think this one has). No forum or online source has been able to provide any clear info, except saying that everything won't work.
2005 Armada LE 4WD (JBA catback, stock airfilter, Eibach springs, Bilstein 5100 front/Rancho RS9000XL rear shocks, Nokian Rotiiva AT LT265s)
"Good judgement comes from experience;
experience comes from bad judgement."