[DebNJim B]

Thanks for the great reply. That box removal definitely shows a pair of vents there. And the seat video is a big help. I actually saw yesterday in a video where that hidden latch is. They actually make a kit for a release handle for that. I'm not sure why Ford put a latch there that you can't reach easily. They have one on the other side.
Anyway, that would explain why the smell builds up when the truck is sitting and diminishes when you run the a/c or just the blower as that would likely be an exhaust vent.
Hope to get into that later today. I have to deal with dead batteries first. I got 6 years out of the OEM so I guess I can't complain. Then have to cover the pool before the leaves start falling. I will report back.