Fuse number 3 keeps popping. Then my brake lights go out and the dome lights turn on when I hit the brake pedal. What is all connected to that fuse so I can start narrowing down my search.
Have you downloaded the Chrysler factory service manual from www.mymopar.com? Wiring schematics are in them. Even if it might be a different model year or brand of C-body, I suspect they will all wire the same, at least until the 1974-78 models.
I take it you are missing the owner's manual? If you have one, look at pg 60 in it.
From the 1975 Chrysler owners manual pg 60:
Fuse 3- 20 Amp:
Time delay for Ignition Switch,
Light and Wiper, Headlight title lights,
Hazard Flasher,
Stop lights,
Trunk Light,
Glove Box light,
Key in and seatbelt buzzer,
Dome light or C pillar lights,
Map light.