The last thing to do is install the 3/8x5" bolt that goes thought all 3 bracket pieces and is the pivot point for the Compressor.
You have to install the nut at the end of the bracket (have it ready) before you push the bolt all the way though. You can not get the nut in place if you push the bolt all the way through first.
Snug the 3/8" lock nut down, but not too tight that you can't rotate the A/C compressor.
You also need to install the adjuster nut for the Compressor. Using a 3/8x1" bolt, flat washer and lock washer, put it through the slotted bracket and bolt it into the bracket behind it. There is a nut welded onto the bracket behind it. Snug it up for now so that the compressor doesn't flop around.
You can now tighten down all of your bolts, don't forget to do this