87 Firebird Speedometer Not working...help!

I have an 87 Pontiac Firebird that was a 305 Fuel Injected converted to a 350 Carbureted with an electric speedometer and digital gauges the speedometer isn't working was told there was wires in the computer harness to connect to the engine harness but no luck finding anything any suggestions or anyone have a diagram? Thanks! :runaround:

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