I did a search and came up with a few ideas to try, just wondered if anyone else could offer some more insight. I just put in a D60 into my truck and lifted it 3" at the same time. I did a shackle flip in the rear and moved the factory lift blocks to the top of the spring to reduce the amount of lift from 5" to 3". Now my speedo bounces around at about 50 mph. This makes the cruise act wierd as well as the E40D. I checked all the wiring and the VSS (or ABS) sensor and it all looks good. The threads I searched though mentioned a bad PSOM. I dunno if it just went bad as a coincident, or if it is something else.

 

It's a bad PSOM. Mine does the same thing, has the same symptoms, as well as a new speed sensor in the rear to rule out that part being bad.

John

 

I was hoping you WOULDN'T say that. oh well, time to take it in the azz at the Ford Dealer...

 

Look in the yellow pages first to see if there's a speedometer shop nearby.

 

Call Southern Electronics in VA, www.instrumentclusters.com I just fixed mine today. 40 minutes R&R time. They are great people.