When I did my front clearance lights, I found the same caulking. I had to dig it out and also push some in. Once the caulking is out of the way, I was able to pull about 6" of wire out. With the wire exposed, I cut the old light off. Then I use a new LED unit and used waterproof connectors. Screwed it into the same holes and sealed it up. Look wonderful when it was done. I also did the rear and it was the same as above. Good luck. You should have extra wire in there too.
Scott -- Commercial Point, Ohio
2004 Damon UltraSport
Freightliner Chassis, Cat C7