I finally got moving on my speaker board. To help get it in to place, I cut the piece to be a tight fit. I can’t take credit for the exactness of the cut, it just happened that way. I catch a break now and then. I used my rubber mallet to pound it into place and angle. Once I got it where I wanted it, I then glued some blocks behind the speaker board to the cab body. These will be the anchor points for the speaker board. I put tape along the space where the blocks and speaker board would be touching as I did not want to glue the speaker board in permanently in place. I marked where the blocks met the board and then put some right angle brackets in place so that the speaker board would always land at the same spot. Then I trimmed off some of the wood on the speaker boards 
so that I could get the speaker board in and out more easily now that the attachment blocks were in. I then screwed the speaker board to the wood blocks. Clear as mud?
I also put up the marquee light board. I used 2 small pieces of wood and glued them to the cab body. Once they were dry, I screwed the marquee light board to it.
Being that there are to be electronics in this area, I did not want anything to be permanently held in place with glue. I wanted to have access to the speakers, speaker lights, marquee lights, or anything else that might get tossed in over time. So everything in this area was built with the idea of using screws for final placement.
