Originally Posted by babymog

Then it doesn't have a left rear speed sensor.

In which case, there is a single rear speed sensor, on the nose of the differential. Check that, the wires might be in bad shape, being a southern car you might have disturbed some brittle wiring when working on the bushings. It is plugged in behind the right side of the rear seatback. I don't remember the resistance to the sensor if good, but if you pull the seatback you can measure it there. I believe (but don't know) that all 124s with the 3-channel ABS (pretty much everything except ASR cars and 4matic cars) have the same rear speed sensor, you might get lucky finding a used one locally.