The problem started with a intermittent ABS light. The mechanic changed the VSS sensor and broke the connector which he jerry rigged. The ABS problem wasn't solved and now the speedometer jumps above 70 mph. He had no idea what to do so I took it but told me I probably need to replace my ABS module behind the Glove compartment which I did. This did not solve either problem. I read that by disconnected the ABS Module that it may solve the Speedometer Problem but I did not want to be without the ABS control.
I took it to another Mechanic and he replaced the connector with a used one and swiched out the VSS sensor with a used mental one.. This didn't solve either problem. He switched out the ABS module with a used one and this didn't solve either problem. He didn't know what else to do. He thought it might be a wiring problem. I tried a third new VSS sensor but no help.
I took it to a third mechanic that seem to know what he was doing. He found a bad connector and switch in the master cylinder that causes the intermittent ABS light. He had my speedometer rebuilt but that did not fix the Speedometer jumping problem at 70 mph. Sai I should just leave the ABS module unplugged since the Antiskid system wasn't that good since it was only on the rear wheels.
Since I have a trailer, I didn't want to be without the ABS system so I checked the wires from the VSS sensor to the ABS plug and module they were good. I cleaned the ground connections to the dash from the engine block and checked the grounds to the ABS module and they were good.
Can anyone help me. I don't know where to go next.

 

I can’t remember what year they changed to electronic speedometer, but IF have a cable from a drive on the transmission to the Speedo, it needs to be lubed.
If applicable you will need to disconnect it at the Speedo and pull the inner drive cable out and wipe it with a light white grease

 

This is a electronic speedometer. That is why the truck has a VSS sensor and ABS Module.

 

Vss has been replaced at least 3 times, cluster has been rebuilt and checked most of the wiring that involves the VSS. I still have to replace the Master Cylinder which started the hole thing with a intermittent ABS light.

Thank you for the ideas but it seems I have tried everything brought up so far. I have been hoping someone had a new idea that I haven't tried.