Is there any way to bench test the speed sensor in the rear diff? I have a no speedo or odometer issue that is driving me nuts. I pulled the cluster and had a local speedo shop bench test the unit and completely clean it, rewired the speed sensor from the connector on the sensor to the connector inside the trunk area, checked grounds from there to the front of the car. Looks like this is the culprit but I dont want to shell out 140 bucks if I dont have to. Any thoughts are appreciated.

For something like this that rarely fails, I would spend $10 for a sensor from a PnP. I suspect they are all the same for the 2/7/9 series.

They are not all the same actually, which was a surprise. There are 3 different ones that are obviously fairly different. I don't know what came from what though, a friend has all 3.

I can see the IRS cars being different but the solid axle cars have no reason to be different...but I do not doubt what you are saying. It is like having two totally different distributors in the same year, for the same motor in the same car. Who does stuff like that?