[Axle]

Rear harness comes out of the firewall, runs to the rear cross member on the drivers side inner frame rail, in this area it will terminate into weatherpak connector (if you have a late square) or a round 4 pin connector laid out simular to the heater blower resistor. On my '83, the termination point is at the center of the rear cross member. I've seen other trucks where it has terminated at the frame rail as well.

Switch over between weatherpak & round was probably mid 80's or late 80's. And that mates to the rear lighting harness with the corresponding connector. In chengys image above of the lighting harness, you can see the connector is a 4 pin square weatherpak connector. 88+ trucks use a 4-inline weatherpak connector.

The round connector is bad for letting in moisture and the wire starts to corrode internally starting at the connector and migrating along the wire. Mine, I've had to cut out about three feet of bad wire to get to some good material. I spliced on a randomn weatherpak connector that I had handy, some people just splice the wire forgoing a connector, which may be what occured on your truck if you can't find any connectors. They just hang there exposed, so if it is there it should be apparent.

Alex.