I thought rather that install a incandescent bulb I’d upgrade to LED. First step is to remove the fixture from the truck. Test the switch with a meter and if it works move on. This would be a good time to replace the switch if needed. I still may need to do this.
Cut the wire and remove the center bulb contact. This leaves a nice passage to run wires.
I picked up a 3 LED bulb from my local electronics store. I’m sure you could get online. It is 12 volt.
Peal the tape cover and stick it to the fixture and run the wires though the hole.
Crimp on a connector to the wires. I solder and heat shrink mine but I like to over kill. I drilled a hole for the ground wire to run it to the front.
Added a connector to run a screw through when remounting your fixture.
Don’t do as I do of the day. Don’t install the headliner and windlace before running a wire to under the dash from the fixture. Since this is such a low current draw I was able to fish a very small wire over the headliner and down the piller under the cardboard. It would have been so much easier to have done this before hand.