The seam between the end cap and the rear valance didn't have seam sealer, it was left open. Now, the seam between the end cap and the quarter did have seam sealer. That seam is exposed to the inside-trunk area. The cavity behind the end caps wasn't filled with anything.

Troy
Houston Mopar Connection Club
'69 Charger Daytona 440 - auto - 4.10 Dana (now with 426 hemi)
'69 Charger 500 440 - 4speed - 3.54 Dana
'70 Road Runner 383 - 4speed - a/c (now with 440)