Quote Originally Posted by 1BadAction View Post
However the speedo is driven in a factory stock truck. I think the signal is split at the DRAC, one signal goes to the PCM and the other to the speedo, but I'm not sure.
If you're running with a DRAC (VSSB to some) and the speedometer works, the VSS should also be working. Either the DRAC output to the PCM failed or somethings up with the PCM itself. As mentioned, swapping PCM's would be a good start.