JBL amp pin-out wiring diagram for 4th Gen Tacoma

Long story short, I'm trying to access the speaker wires that go to the rear door speakers at any point after they've gone through the door grommet and into the cab. I am not looking to connect my new speakers to the JBL amp. Getting rid of its weird frequency/crossover mix is the point of the project. I have an aftermarket amp connected at the headunit through an AP4-TY14 which gives RCA outs.

I'm looking for a JBL amp wiring diagram/ layout of the harness pin-outs. These seem like they've been hard to come by. I was initially going to locate the wires after they traverse the door-cab grommet, but they come out of the connector a different color than the red/white pair on the door-side, so I'm not sure which wires to access on the cab side, and they might be more easily accessible at the amp under the driver's seat.

I was able to run wire to the front door speakers through an empty slot in the wiring harness at the door, however this was a serious PITA, and I don't think it will be as easily accomplished on the rear doors.