Wiring Gauges Into Car - Electrical . GAUGES These are the correct 1968 Shelby console gauges. The gauges were specially made for AO Smith by Stewart Warner. They are similar to other gauges in Stewart Warner's "green circle" performance gauge line.. Wiring a 69/70 XR7 Tach into a non-XR7 car Also see: "Installing an XR7 tach in a 69/70 Standard cluster" below. Installing an XR7 tach in a 69/70 Standard cluster.