Hey guys. I mounted some small, solid sounding home theater speakers to the slightly curved panels left and right of the rear window on my `67. I used 3M double sided tape, ran the wires thru the rubber plugged holes in the panels, down and under the door sill trim. Real neat and sounds good. Those little speakers can handle the watts, and no "sonic boom" of magnets or mounting screws into sheet metal. The 3M tape has a thin foam core that isolates vibration.
Nah, no pics yet, one of these days I`ll get around to figuring out how to do that, or get my wife to show me how. I barely know what I`m doing just to keep the old beast roadworthy. The speakers are roughly 7x5x3, typical home theater sattelite speakers. The back sides just happened to be curved almost perfectly to fit the contours of the panels next to the window. The wires are covered by the speakers where they enter those conveiently placed holes in the panels. Looks neat, sounds great! And yeah, I need to figure out how to post pics, I`m real proud of my old truck and I want to show her off!