i have a 85 berlinetta with stock digital gauges and i am have a problem with the speedometer. it just doesn't work tried changeing the plug on the side of the tranny that didn't work i need to know where i can get a new plug, and if the speedometer runs through the computer or not, and if so if there is any way of by passing it.

 

If the speedometer readout is "black" all the time than you probably need a replacement cluster.

If your Speedometer always reads zero than the Speedometer sensor in the tranny of the Speedo Buffer Is to blame. ( The speedo buffer is in a little yellow plastic box on the drivers side under the dash or behind the kick panel. )