Bouncing speedo....need new gauge cluster

[Grebesbakery]

I have the bouncing speedo like many of us do, from what I have read messes with the tranny.

I have been looking at getting a used one off ebay, BUT I have a few questions.

First, does it matter if the cluster is out of a diesel or gas?

Second, little worried if I buy one I will run into the same problem...feel like there may be more bad ones out there then good ones.....what do you guys think?

Thanks

[superduty4x4]

Diesel or gas won't matter. If you get a gas cluster though you'll want to disassemble it and put the speedo into your diesel cluster. The more important issue is to make sure you get a cluster from a truck the same year as yours. There are minor wiring differences between years that can cause minor problems.

[Patrick Feeley]

Have you checked to make sure it's not the Vehicle Speed Sensor (VSS) or tone ring in the rear end? Cheers!

[Grebesbakery]

I have not checked the VSS or the tone ring....agian i'm new to all this....

What exactly am i looking for and where is the VSS.

thanks!

[superduty4x4]

The VSS is the sensor on top of the rear differential. One bolt holds it in, then you should be able to wiggle it loose and pop it out. Fine metal shavings on the sensor are normal, any large chunks would be cause for concern. I'd suggest buying the VSS from Ford if you want to try swapping it out, the parts store units tend to be more problematic (it's only about $25 from Ford).
Inspecting the tone ring requires removing the rear differential cover. If you don't see any large chunks of metal on the VSS, I wouldn't worry much about the tone ring.