Dodge D-350 Cummins Speedo/Speed Sensor Problems

[GLHS592]

My speedometer quit working in my 2wd Cummins 5-speed Ram D-350. I installed a new speed sensor from O'Reilly's today. Now, the needle jumps all over the place at any speed. The needle will pretty much sit at zero when the truck is stopped.

I noticed that there is an "L" shaped part between the transmission and the speed sensor. Should I be able to move it? It is loose and I can move it all around when the nut is tightened all the way down. I took it out and tried to spin the "needle" with my fingers. It would spin at times and other times I had to press down to get it to spin. It sounds to me like I will need to replace this part also.

Thanks in advance for any help!

[highpsi4]

Well, I guess this is probably very late but if the needle is jumping around then you have a problem in the cluster. The drive gears for the speedo needle are plastic and break/wearout. This causes intermittant contact so the needle jumps all over the place. On mine when it is jumping around if I push the trip odometer reset it pushes the gears back in line and it works good for awhile.

[GLHS592]

There is a speed/gear reducer between the tranny and the sensor. It was the culprit.
http://www.transmissioncenter.net/HPIM1498.JPG