69 fury trunk floor question

i have many pictures of the trunk floor that i have saved from the internet but none show the area i need. where the trunk floor and the drop off meet there is a seam. underneath that seam is a flange. is that flange one sided (drop off only) or double sided (trunk floor and drop off)? in my mind it would be a doubled flange, spot welded together from underneath but i don't know for sure.
Author: 1970cat