Stereo install question...am I missing some brackets here?

[shiner2001]

When I picked up my 90 Suburban it had no stereo, so I wanted to put a CD player in the factory location. I have all of my wiring done (previous owner cut the factory harness out, too) and picked up a Scosche GM1504 installation kit, but for the life of me I can't figure out how it's supposed to mount. I have installed stereos in everything under the sun and am fairly mechanically inclined, but I think this truck must be missing some brackets that I am supposed to have or something. The kit fits the hole in the dash great, but there is just no way for me to see to mount it. And as a universal kit, the instructions for each application are vague at best. I snapped a couple of pictures; if anything glaring is missing, I'd sure appreciate a heads up. It won't be too difficult to fab something completely from scratch, but if I can save myself the effort that'd be great. Ideas??