[Peter Serio]

That looks like a plastic reproduction tach from about 15 or 20 years ago.


If it is, indeed is one of those, whoever made that had absolutely no clue as to how the dash gauges are suppose to light up at night.

Here are a few photos of that plastic tach opened up ( side by side next to a GM original 64 GTO in-dash tach) so you can see what's wrong with it.

You would need to take yours out of the dash and open it up to try and see what you might do to improve the night time lighting. There are 2 bulb sockets that go to that tach, they both plug-in from the backside.

The interior of any '64 GTO tachometer housing including the backside of the circle dial ought to be painted in several shades of light blue (so as to reflect the light coming from those 2 bulbs). To make the one you have better for night time driving you would need to study an all original '64 GTO tach opened up so you can see how GM did it. To start with I will post a few photos of the one I think you have. The housing to that is most likely made from black plastic which is a problem as the black can't reflect any light off of the bulbs.