> I have an amplifier all hooked up in the cab, original wiring harness, etc. I just
> need a board to connect the RCA plugs from the amp to the board.
Every PCB I've seen with stereo out uses a 4-pin Molex. If you have one of the old CD audio cables that went between your CD-ROM drive and soundcard that can usually be hacked up to work. Female RCA jacks on PCBs wasn't a thing until JVS.