This is a New Tachometer for IH Farmall tractors.
Part #s: 388589R91 388588R91 66748C1
It has a black face and 2 light terminals.
This will replace the original with the only difference being the light terminals.
This has a post with a hole in it and a set screw.
The light bulb fits into a socket that is pushed into the back of the gauge.
It makes a better sold connection than the originals.
Fits IH Tractor models: