I did some searches, and I couldn't find anything on what equipment Rick used on the Brown Album, so I figured I'd ask some of you scholars on TB.
I'm pretty sure this was before Rick had his ampeg fretless bass, and definitely before his Gibson Rippers. My guess is that it is just a good ol' Precision bass with flats, maybe through an ampeg head, with a pick. It sure has some beautiful warm percussive rumble to it.
Here are two songs from it, to see if any of you can analyze the sound.
http://www.youtube.com/watch?v=xUPbIbHUem0 http://www.youtube.com/watch?v=vRTuarR_SmE