Speedometer and boostgauge not working
 

The supra i bought recently doesn't have a working speedometer, it gives me oilpressure, rpms watertemperature, but the boostgauge remains at bottom -2, and the speedometer won't budge.

The previous owner changed the headgasket on the car, is it possible he forgot to connect them?
If so, anyone got a good description or picture of the locations of the senders for these gauges, so i can test those before i rip my dashboard open.