Matt - pretty cool pics - I'd protect the identity of your friend as Ford probably doesn't want a lot of pics being snapped on the production line

The pics are of the under rear seat floor pan - I recognize it from when I installed my dynamatt and the two holes are access for the undercar - front of fuel tank area that will be plugged with rubber access covers. The last pic looks to be one side of the rear passenger footwell - not sure hard to tell how wide it is in that pic!

thanks for sharing these pics with us and to the commment on if this is the orig production plant - this is actually a brand new plant built for Mustang production.....the old plant was closed after the last of the '04's rolled off. I had read that the former plant was so worn down that the floor pan stamping machines were worn out so badly that the line employees somtimes had to finish the stamping by hand with hammers......

 

The left picture is the floorpan. The two holes are access panels for fuel tank. The right picture is an upside down view of the rear floor. I think that's the spare tire well. The scoreboard shows what vehicle is currently in the bodyshop and whether it's coupe or convertible.

It takes two days to build a complete car so if your buddy tells you he's watching it to make sure they torque every screw right.... he better bring his sleeping bag!