Hi All,
Well, I am officially confused. I ran two tests which should have been mutually exclusive and they both were positive

1) I hooked up the speedo cable to the ratio adapter and into the tranny and disconnected the speedo cable at the speedo end - I then pulled the speedo cable end into the cab so I could hold the inner cable itself between two fingers to see if it was rotating when I did a test drive. I took a 1/2 mile test drive and the cable end I was holding was rotating and increased rotational speed as I increased truck speed - I also applied as much pressure as I could to the cable and it continued to rotate - this indicated that the tranny, ratio box, cable portion (at the tranny end) of the circuit was all working, as it was delivering a a spinning cable to my fingers while I was driving - this indicated to me the problem must be in the speedo - I hooked the free end back into the end of the speedo and took another drive - no speed or odometer moment, indicating to me a bad speedo

2) After waiting for the exhaust to cool, I slid under the truck unscrewed the cable from the ratio box hooked it up to my drill and had a helper watch the speedo needle - much to my amazement, both odometer and speedo needle moved - I was able to get a full needle movement with my drill up to 90MPH -

One of these tests should have failed - first test indicates speedo/odo gauge bad, next test indicates speedo/odo good -

The only thing I can think of is that the end of the cable might be slightly disengaging when I hook everything up and not when I use the drill - I.E. there is something with the speedo cable itself - the other thing I can think of is that the adapter, while spinning, might not have enough torque under load ( although I squeezed the cable hard as I could to try to give resistance in test #1 above ) - I am otherwise at a loss - I was expecting to be here asking how to remove the speedo and buy a new one, but the cost of ~$350 made me retest again - I would sure appreciate some suggestions here

Joe Finkelstine
Born and bred in Motown