Want to put and aftermarket tach in a rallye dash

That looks great 72, are you going to trim the sides down a little so the factory back lighting will light up the gage face?

Nope. The tach has its own light, and that clear ring in the cup is a disperser for the light that goes in the back of the gauge. Gives much better light than the stock set up.

When that tach gets installed I’m also running LED strip lighting inside the cluster to brighten things up, I’m doing away with the stock lighting.