I was cleaning the inside of my truck and I found this adapter behind the cup holders. What is it for? I have never seen it before.

 

undo the screws for the cup holder and look lol

 

If that is a 1998-2000 it should be part of your air bag module. Pull out rings in the cup holder (plastic), remove the rubber insert from the bottom of the cup holders, and you will see two screw looking plastic pieces. If you take a really big flathead screw driver or a quarter you can turn them 90 degrees and you can then take the cup holder out.