I'm estimating it's a 1/2" dia hole.. but Click can measure his better, since his didn't have a wire going thru it.. (a drill index works well for measuring hole sizes)..
PS. I found an old TC posting that also says 1/2" hole.. (Note: Holes go on the OUTER side of the brace on each side).
"Jun 15th, 06, 04:37 AM
if you look at the bumper brace that welds to the tailpanel and the trunk floor that the bumper bolts go through you will see a half circle cut into the brace where it sits on the floor. that is where the pigtail wire goes (1/2" hole). you'll have to look at your taillight harness to make sure you pop the hole on the correct side of the brace as they are interchangeable left to right and have the cuttouts on both sides."