Dash light wiring

[Detroit Bill]

I replaced the factory speedo today with a Smiths GPS unit.
The install went well and during the brief test ride it seemed to work well.

The stock gage has two wires a black and a red. The new gage just needs power for the light. Which is line which is ground?

I can test it but I did not have a meter when it was apart.

[Gaz64]

I would say red to the light wire, black to the gauge case metal.
I would test the red with a testlamp to ground to prove it is 12 volt +.

[Randy Rosenberg]

1. Buy the wiring diagram from Blas.
2. I once made the mistake of assuming Black was ground. I think Brown is ground.
3. When in doubt, refer to #1 above.

[Detroit Bill]

With my incredible organizational skills I have miss placed them!

I'll just check voltage and continuity to ground. I did not have a meter at home, I'll grab it from work.

The wire colors confuse me. Brown is ground. It does not seem to follow any convention I am aware of.