Used with Parliament and Funkadelic, as mentioned by Collins in this excerpt from a 1979 Guitar Player interview as transcribed TalkBass here and here from a reprint in Bass Heroes: Styles, Stories & Secrets of 30 Great Bass Players.

What kind of amps do you use in your setup?

The entire system is divided into three different parts - high, mid, and low. But we're not just talking about amplification, we're talking about the effects in each part. On my highs I use a Big Muff fuzz, a Mu-tron III [envelope-following filter], an MXR digital delay, a Morley Fuzz/Wah, a Morley Power Wah, and an Eventide Harmonizer. The Harmonizer sits in a case that looks like R2D2 from Star Wars. It looks just like a little robot, so I call it R2FunkU. There's a sign hanging on it that says, "Can I Play?" Inside of it, there's also a keyboard for the Harmonizer that enables me to preset harmonized intervals to what I'm playing. That way I can play a note and have a fifth or a third coming out at the same time.

All of that equipment just for the highs?

Right. For the mids, I have a Big Muff fuzz, a Mu-tron III, and an MXR digital delay. On the lows, I use a Mu-tron Octave Divider, two Roland Space Echos, a Big Muff fuzz, and a Mu-tron III. I keep all my effects in one box called the Space Case. The highs and mids each have an Alembic preamp, two Crown DC-300A amps, and four Cerwin-Vega speaker cabinets.

What's in each cabinet?

The cabinets used for the highs are called V-32s. They have two 12s, one midrange horn, and two tweeters. The midrange cabinets are basically the same, except there's one 15" speaker instead of two 12s. Those are called V-34s. On the bottom end are three Acoustic 370 heads and six Cerwin-Vega cabinets. Two have one 18" speaker and one 12", two more have an 18 and a 10, and two have one 18" and an 8.

Isn't that a lot of equipment for onstage?

I don't play it that loud. I've just got it there so that I don't have to strain the equipment and everybody can hear. As a matter of fact, the whole stage is set up like that. The guitar player, the keyboard player, everybody is set up like that so there is no real strain.

https://youtu.be/fnzKZFWnY6w?t=36 Video of Jerry's Rig

"Studio and live equipment has usually been similar to the above throughout the years, sometimes with the addition of acoustic bass amps i.e. a 370..."

The bass rig fans most associate with you is the Acoustic 370 head and the Ampeg 2x15 cabinet. Were there any specific reasons that you settled on that combination?

At some point fairly early on, I came across an Acoustic 370 head that someone told me might be good, so I bought it—it wasn’t expensive. That head paired with my cabinet sounded pretty good. Those heads are so loud. I have never played with mine turned above about 3.5.

Peter’s main amp according to this interview