mechanical/electric gauge grounding

[frankyjoet]

i replaced a sending unit in the gas tank on my 73gmc. the sender was properly grounded. with the key on the fuel gauge still went to 3'oclock. the pcb grnd wire grnds 3 gauges. the mech. temp/mech. fuel and the electric oil gauge. with a meter tester all 3 grnds on the gauges were good. power was good to all 3 gauges. is there any way these 3 gauges can be grnded individually. next step is to test the gauges from the battery. thanks for any help.