Remove the old one and look on the side of the bulb base.
I do not believe there is a metal bumper. There is a foam insert that goes inside the bumper cover.
The 04 is common for a broken wire behind the door panel...usually when it comes out of the door and goes through the hinge area
buy the 50/50 blend premixed green i have a 99 jeep Cherokee also
its a pulley fan, it never goes bad
It is under the housing where the upper hose goes on the engine.
Automatic transmission fluid
It goes into the top of bell housing.
I had the same problem, all I did was replace the fitting that the bulb goes in with a new one ( $8.00 fix) and replaced the tail light and haven't had a problem since.