Sovagary, I got a radio from Custom Audio Sound, mine is the
USA-3. It had a metal bar that attached to the back of the radio and then I bent it and attached it to an existing hole in the dash with a pan-head machine screw. The knob shafts are threaded and you have a nut, then a washer on one side of the dash, and then another washer and another nut on the other side of the dash that holds it quite snugly in place. I opted for the upgrade since it has AM/FM with 12 AM presets and 18 FM presets and the option for more speakers if I so choose.
The stock radio, IIRC, is held in place with the knob bezels and a nut on the back side of the dash.
For the speaker, I have 2 3.5" speakers in a thin board that is the exact same dimensions of the grille in the dash. I put a machine screw in each corner through the grille and put washers and nuts on the other side of the board to just hang it in place. The speaker that was in it was hung in a similar fashion, I doubt that it was the original one.
If you can wait another day or two, I can get some pictures of my set up and post them here. A good person to talk to is 4-5-6 Chevy Trucks, I think all of his trucks are bone stock and have NOS parts in them. You may want to PM him and find out exactly how the original stuff is mounted.
