If you get the firestone airbags (I did), call and tell the guy you want the same diameter air bags as the book calls for, for the Armada, but you want the bags that are one inch taller. That way, when you fill them, there won't be any bag to spring space at the top and bottom of the spring.
Next, current air bags (all inside the coil spring manufacturers) have junky push to connect fittings. You'll have to repressurize them every other day. I cut a 14" section of the airline, inverted the bag, and sealed the airline entry to the bag with JB Weld. Inverted for gravity assist of the JB Weld working into the nooks and crannies. Went to Ace Hardware, got some brass compression fittings to connect the air lines back together at the 14" mark after install into the coils. Installed them per instruction side up, air line at bottom. That increased the repressurization interval from daily to weekly. Since I'm lazy, and my Firestone airbags I had in my '77 didn't need to be repressurized but once every 6 months, I looked deeper.
The airline intake valves (shraders) are made in China....... So, I found an air suspension component company that makes parts for the low rider cars that have the computer controlled "dancing" suspensions. Got a couple one way check valves for the airlines. (screw together brass compression fittings). I lost 2psi in the last 40 days! Much better! - just a consideration. Can't remember the name of the check valve company. (age)