The easiest way to tell if you have a reproduction or original gauge is to look at the movement case, If you look at the picture below you’ll notice the original has a dull zinc finish to it while the reproduction gauge is shinny.
You might also notice on this 1978-1982 style gauge that the original has three brass studs and the reproduction only has one.
Another way to tell is the finish on the back side of the face, typically the later gauges have blue as shown and the earlier gauges were green. On the reproduction gauges the paint of the back side of the face is shinny, regardless of what color they are all reproduction gauges have way more gloss than the originals.
Why is this important? It’s very important if you are trying to use our temperature gauge adjustable resistor. Original gauges had resistors on the outside of the gauge, reproduction gauges have the resistance inside the gauge. If you try to use our adjustable resistor on a reproduction gauge it will not work. It is a very common practice for people to install the reproduction gauge and use the original resistor (because they didn’t read or see the instruction sheet inside the box), this will cause a new gauge to malfunction.