Dance as in shakey reading? If it like bounces around a few MPH, that's normal. If it's reading more than 5 MPH off, then it's time to check other things. Like maybe lube the cable first and if that doesn't work, change the VSS and/or speedometer head.
Cecil, I'd try looking at the speedo cable to see if it's got a kink in it. You could try lubing it, but after 9 years, it's time for a replacement cable. Be sure you use the blob of grease on the speedo head end of the cable when you replace it; that helps to dampen the needle bouncing.
I also have a 1995 with a 3.8, but my Sable has the digi-dash, so there's no needle to bounce.
Well, It reads fine up until about 50 mph. Then, all hell breaks loose. It goes up to 85 down to 40 any where in between. And it makes a grinding noise. At exactly 55 mph (kinda funny its there) it squeaks like a pig. I remember from the past someone mentioned it was common for these cars and the only way to fix it was to remove the speedo from the cluster and have it dismantled and repaired. Is this documented from ford? Did ford ever issue a statement one way or the other? I am probably gonna sale it and I'd like to be able to tell the new owners something other then live with it like I did.