I bought one of these and removed the black part so I could use a nut to secure it to the blank switch. Plus I can just plug my RCA-to-3.5mm cable into the back, no soldering or gluing.
I completed this project today. Which part are you unclear on? Pin 39 should be connected to pin 40. Pins 37 and 36 connect to the right audio channel. Pins 35 and 34 connect to the left audio channel. When facing the back of the stereo, pin 40 is top right. I used female RCA connectors (center is p...