Brute force with some side to side movement will get it out.

The air filter box is held in place by 3 or 4, I forget which, tabs with rubber grommets on the bottom. The grommets engage in about 1" holes in the body under the air box. After you remove the air filter top and get it and the associated stuff out of the way try working your hand down under the air box at the left rear corner and pull up while wiggling. That should disengage the back left tab and from there it's easy. Remember there is a short air intake hose running from the air box to the grill. Installation is the reverse BUT remember the rubber grommets need to be mounted on the tabs before you attempt to intall. I found a bit of silicone spray on the grommets helped. You just have to kind of feel around until everything lines up and then push down hard on the bottom of the air box to get it to fully seat. Not very user friendly but it can be done.

Other notes. 1) while the air box is out check the hose to the turbo down low and see if it's ripped as the lower end tends to get oil soaked and come appart (replacement cost ca. $55). 2) per Squeeto (viewtopic.php?f=5&t=56486&hilit=citric) cut 2 cms off of the handle of a 10mm "Allen" wrench and insert that into the hollow head of the radiator drain plug; now you can turn it with the open end of a 10mm wrench or even better a ratcheting 10mm wrench. 3) after you open the radiator cap on the firewall tank don't forget to open the vent plug on the upper passenger corner of the radiator to help the system drain faster (that plug can be removed); when you refill do so from the firewall tank until fluid comes out of that plug to purge most of the air from the system. 4) no one really knows the capacity of our systems and the manuals are not consistent IMHO add 6qts of straight Zerex G-05 and top off with water to get to the recommended 50/50 mix.

Thanks for the detailed description. I was wondering about that radiator plug. For the drain cock, I ended up using 1/4" drive wobble extension with a 10mm hex socket. I put a wrench adapter into the drive end of the wobble and then used a 14mm gear wrench to turn the extension. May whoever designed the drain be relegated to the place of eternal damnation (General Motors?).

There is no problem getting to the drain plug from underneath.

Brute force with some side to side movement will get it out.