1950 chevy 1 ton with '62 261. New rebuilt gauge cluster.. For 12V system. New sending unit from lmc . Resistor from lmc for 6V to 12V on sending unit... Resistor in power supply to center post on sending unit. New ground wire from sending unit mounting screw to frame (clean connection). Didnt check any of gauges or sending unit before install.. Rest of gauges and instruments work fine.. Just having trouble with this one circuit.