The tack strip was in the original bath area, along any series of rivets that held sections together.
I'll try to post some photos. This one is of the vanity. The tack strip is white. The top section of the vanity is riveted to the bottom section. The rivets are hidden by the tack strip.
In this image, the cover that snaps over the tack strip is missing in the horizontal top piece, so the rivets are visible. The vertical piece at 90 degrees still has the cover in place, so the rivets are not visible.
If these photos don't make it, I'll try again later.