I've never really understood that. Deaf people can drive. People in fire trucks and most government trucks wear earphones. Many people drive in cars with 1.21 gigawatt stereo systems that you can hear from a block away with their windows closed.
Anyway, I built an 'L' shaped shelf that sits on the front and side lip of where the roof is bolted to the sides and windscreen top.It holds the radio and a speaker at each end plus a CB radio and clock.
I no longer have the original image but you can see the shelf in this collage:
Thanks Terri, I like the idea of things like radio components above head. Interesting set up. Thank all,, ver
La Salle Trim make a range of headliners for ceiling mounted radios and speakers.