This was for a '95 Chevy 1500 flatbed with farm plates. The sole purpose of the truck was to get me from home to the dock and back again. I spent most of my time in the GoM at that time, and it was about a 2hr. drive back and forth depending on which dock I left out of. The tape deck had quit, and that was an issue because I couldn't listen to books on tape, or any of the music I had. I think that napster was dead at that time, but limewire was still a thing.
I had a PDA ( I can't remember what it was, but I am pretty sure it was a compaq, and I know it had a gps antenna). It had a dash mount, and an adapter cable. I don't remember all of the details, but I cut the end off the adapter cable, and figured out the outputs on the cassette deck and used the BasicStamp to switch the radio into 'cassette' mode when it detected an audio input from the PDA, and then the PDA would play through the truck speakers as if it were the cassette deck.