Speedometer issue

[djembeing]

Ok, I was doing about 55 mph and all of the sudden the ABS light came on (check engine has been on, Advanced Auto checked it with a computer and said it was a vacuum leak) Then the speedometer started flopping around like a fish. Now it doesn't work below 55 mph. It rests at zero until I get to (i guess) 45-50 when it starts flopping again, then 55 and above it's fine.
I read about a similar problem, something to do with the ABS sensor. Is this something I can fix/replace?
Ideas

Thanks
Dave

 

[Hunz]

The only suggestion I have is to replace the ABS sensor. The sensor is on top of the rear diff and only takes about 10 minutes to replace(not that expensive either $20) I had my ABS light come on and that fixedit for me, but as for your othert problems that is a weird issue.