I would pull the connector at the speed sensor on the rear diff and clean out both sides good, check that the rubber seal is in good condition, then reassemble and see how it goes.

 

I am gonna get it in a heated garage when I get home and follow the harness forward from the rear differential to check for bad connectors and frayed wires. I'll also clean the connectors real good and use dielectric grease.

 

any luck???

 

I got home and fond 8 inches of snow in my driveway and got it stuck. Of course the guy that plows for me was out of town and I couldn't get anyone to plow till late yesterday so havent done anything more.

 

During our latest cold snap, I now remember it was my tachometer that was fluctuating, not speedo. Could still be issue with moisture though. ??

 

The strange part is it doesn't do it in warmer weather even when it is raining.