2003 mazda mpv speedometer
 

I have a 2003 mpv that the transmission was recently changed out on and now the speedometer does not work, the vehicle has been to the dealer 3 times and each time they have come back with a diffrent answer. 1st they said it was the abs sensors so those were replaced and did not fix the issue, then they said it was the cluster that was bad that was replaced and did not resolve the issue, then they said the ecu must be the issue so that was replaced and did not solve the issue. So my question is where does this vehicle receive its speed signal from and has anyone else had a similar issue? This has become very frustrating and the dealer seems to have no idea what the issue is so any help would be greatly appreciated.