On the right hand footwell of my 1987 coupe I just noticed a hole in the floor. It almost looks like it should have a bolt since it’s quite round and there’s a nut welded to the floor. Any ideas as to why it’s there?

 

My '87 is the same only the bolt is in the hole, screwed in from the bottom. If you look underneath you will see a horizonal bar a couple inches wide. Maybe some kind of body rigidity enhancement..
I have an '88 I am parting out. I will see if I can get the bolt out for you if you want it.

 

Look on the left hand side to see whats bolted there. These are Right hand drive cars originally.

 

There are two captive nuts in same position in floor ribs in both left and right hand footwells. They normally have plastic plugs in place to seal them off.
Used on assembly line for floorpan to jig attachment maybe ???

 

Since the coffee has wprn off, and the Jameson is on the go.

To let the water out, was my thoughts.

Assembly jig attachment makes much more sense.

I had them on the S2 cars also, and YES, plastic plugs, or remnants of, in that hole.