Viewed from the back the vintage...
Viewed from the back the vintage housing has the new meter is in place with wiring for the sender and internal lighting.
The SN76 tachometer signal adapter will amplify a weak tachometer signal and double the frequency. This is useful for converting four-cylinder computer tachometer signals (computer signals tend to be four-cylinder, even if the engine is an eight-cylinder) to work with eight-cylinder tachometers.
Classic Instruments’ 3-3/8-inch tachometers work with four-, six-, or eight-cylinder signals and some 12-pole alternator signals; 4-5/8-inch tachometers work with four-, six-, or eight-cylinder signals and some 10-, 12-, and 20-pole alternator signals.
Classic Instruments tachometer combo gauges with push-button calibration function are compatible with signals of 1 to 14 cylinders and are also compatible with weaker 5V computer tachometer signals.

To provide space for the updated...

To provide space for the updated internals a spacer was added to the back of the original housing.

With the spacer installed...

With the spacer installed the mount for the new movement can be added.

Our new old gauge looks better...

Our new old gauge looks better than ever. We’ll have to provide ignition switched power to the new gauge as well as a good ground and install the supplied sending unit.

It may look like a bundle...

It may look like a bundle of wires, but this is the business end of an air core movement found in contemporary electric instruments.

It doesn’t look like much...

It doesn’t look like much because it’s not—this is an original Ford thermostatic gauge. The heating element and the bi-metal strip are behind the pointer.

Our vintage mechanical temperature...

Our vintage mechanical temperature used a Bourdon movement. The curved copper tube straightens when pressure is applied to it (due to oil pressure or expansion of the fluid in the tube).