yet another long time problem I'm trying to solve. I have a bouncing speedo - mainly over 60 mph.

I've replaced the VSS in the rear axl with one from autozone. Didn't do anything - if not make the situation worse. Finally bit the bullet and bought an OEM motorcraft one. Still where I was at with the original.

Is there something I'm missing? Can the encoder in the rear axl be bad, damaged or dirty?

It's not a terrible bounce but enough to be noticeable and noticeable when I'm using cruise control. The truck will surge from time to time to compensate for the bounce.

Any thoughts?
Thanks,