I put abs sensor on differential thought I fixed everything but now when I go over 60mph the speedometer drops to zero and o/d light blinks. When I lower speed below 60mph it corrects itself. What else could be wrong?

Check the air gape between the sensor and the reluctor ring of the differential; it must be within .005-.045”. If by chance you didn’t clean the mounting surface of the differential; the crud might be holding the sensor to far away from the reluctor? If this is the case; it maybe to late to clean it now for your new sensor; if it was tightened down on top of a dirt ridge the sensor may have warped?
Just a guess on my part; but the replacement procedure goes makes a note of cleaning the area & then checking the air gap?

Dan.

Canadian "EH"