Was coming home from St Germain and the speedo quit working at 70 mph but when I would slow down for the bad roads it would then bounch all over. And today it works like it did on the way up bounchs just a little.

 

That sounds like a bad connection (loose).

Check the plug at the VSS on top of the rear differential for corrosion and tight fit, if the pins in the plug are corroded, clean them and put some dielectric grease in there to keep moisture out in the future.. Also make sure the rubber seal is still in the plug..

If all checks out there just give the wiring harness under the truck a good looking over, something could have flew up and damaged a wire there..

If any one has had the instrument panel out lately, there's a possibility a plug (there are 2 back there) was not latched in properly..

Good luck, these types of problems leave your hair in fear of it's life.. (from being pulled out by the roots)