I believe that I grounded each of them to a bolt under the dash and to the body. The one you show in blue was on the drivers side of the dash cluster and the other one was on the right hand side. It has only been a few months since I put in the new harness, but I didn't trust my memory so I used color coded tie straps to make sure I put them in the correct place again. The ground wires to each of the gauges should be on a continuous black wire with terminals about every 4 to 5 inches. So on these wires just make sure you have a good ground to the body. Charley
