[DKAudio]

I could not find a ram-set nail that would work. Either it would go all the way through the 3/4" wood or it would not go in far enough. I ended up using hammer set masonry expansion anchors. Those things hold like mad. HD did not have 1/4" drywall, had to use 3/8". It sticks out farther than I wanted but hopefully good feathering and a lot of mud/tape will hid it.

Next question, somewhat similar. At the bottom of stairs (after ripping everything out) has a thin duct. I am not sure what this duct does. The ducts that supply my air are about twice as tall (3.5" for the thin and 8.25 for my supply ones). I don't think it is my returns either. This duct goes to a couple spots where they stapled aluminum sheet between the joists. I cannot see what it goes to though.

First, do you know what this duct does?

Second, I want max height clearance to my already low basement ceiling. Can I gorilla glue drywall right to the ducts and then mud? It would only need to be on 2 sides of the duct with 1 outside corner and 2 inside corners. Can I attach my metal bead by piloting and using sheet metal screws going into the duct?

I realize I should probably build a frame but again, I want max height clearance here and it is only for a few feet.