parking light source for gauges

Where is a good source for parking lights to hook up my gauges to? I read that the green light on the dimmer switch is a light source but I can't figure out how to back probe into that.
 
I used the wire your talking about.
I popped off the side cover that's visible when the door is open. Then I could see the dimmer light thingy. I just tapped it and ran a long wire for me to tap my gauges into so when I turn my lights on my gauges change color.
 
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