The piece KBS circled is an inline fuse. It's not a connector that needs to get plugged anywhere. It has a cap and a fuse inside. I could've taken it off since the power line I tapped into was fused already. But it was easier to leave it in.
I believe this is the same harness.
There are several posts on this forum and others that list what color wires go to the four speakers. I didn't want to reiterate them here.
Find the eight speaker wires and attach them to the same color wires on both ends of the adapter harness. Then, black goes to black. Yellow goes to yellow. Red goes to Orange.
Just remember it's a pass-through device. Cut the add-on wiring harness in two. The factory wiring harness from the truck that normally goes into the back of your factory radio will now go into one end of the wiring harness. The wires from that end will attach to one bundle of wires of the Alpine amp. The bundle of wires on the other end of the amp will attach to the other end of the add-on wiring harness. This will then plug into the back of your factory radio.
Sorry for the late reply. I didn't see the notification till now.