‘68 Dart, One tail light not working.

The first device you pictured is a delay relay

The second does not look like a cap. You sure it's not a lamp? What does the other side look like? Shift quadrant lamp?

PLEASE ALWAYS POST the year make model
The title has the year and model. After looking at it again.. it could be a lamp. My shift indicator needle is missing also. The wire going to it is in pretty rough shape and has a splice in it in addition to some spots where it’s been taped up because the wire is showing