On the subject of that Precision, it went through many changes. At one time it had EMG active pickups. I shaped a PCB to fit into its control cavity. I then designed `a seven transistor pre-amp with the Bass and middle controls using fixed resistors at what would be centrer. The treble I brought out in the place of the tone control. Volume in its usual place. For power I used a TRS output jack with a positive voltage on the ring. This was supplied by my amp whose input jack, also TRS, provided 1mA at 48V.
For other uses I built a couple of adapter boxes. One contained a bunch of 9V batteries in series to provide the supply. Another allowed me to plug into a microphone input of a mixer and take advantage of Phantom Power. it all worked amazingly well and allowed me to get some real brightness from the Rotosound wire strings I was using.
The soft metal of the Fender frets. eventually ended the experiment as they wore down too quickly. I changed to GHS Brite Flats ground down wire strings which solved the fret issue but by then I had acquired a Warwick Streamer which became my primary bass until I graduated to instruments with six strings. As for the Precision I rebuilt it back to stock.