New Aetna LED Tachometers

OOOOfhaaa
Would you believe they used almost the exact same fixtures in 1980 ?
Mine look identical but are mounted between the top of the mirror and the ceiling.
Fortunately I have not had the water issue you've got.

Any idea where the water intrusion is ?

I'm aware of a nice Glendinning kit for synchronizing mechanical engines.
As I recall, it has its own mechanical pickups to read the revs from the flywheel.
I didn't know that they also build gauges, though.
Anyway, enough of o/t, and thanks again.
Back to JD project now!

They also build cam drives and electric senders from those drives to feed Atlas or other electric tachs while also allowing mechanical drives to your mechanical tach units. Good folks to work with...

;-) here shows my Austrian (german speaking) origin with humanistic education (ancient greek and latin in school): Tachometer in German is used for (obviously) speedometer, and "tachys" in greek means speed. "Your" speedometer would be a Drehzahlmesser, revolution-meter.

Sorry for any confusion...

I can't find any interior pictures of mine head here.
The fixture looks just like what you have however it is only one lightbar and it runs directly above the mirror.
The bulbs are the same but maybe slightly larger diameter.
Having them so close to the headliner is not so good as it discolors the headliner above the bulbs.
Having them on the sides seems like a better idea.

No worries, I don't think you actually confused anyone.
Btw, I perfectly see where you come from, 'cause "tachimetro" is the Italian (my mother language) for speedo.
Pretty similar to German!