The hinged lids of the 240Z attach using the outer pairs of tapped holes.  But why do both doors have this extra pair in the middle?

I have seen pics of brackets bolting here for the 1977 and later false floors, but why were they on earlier cars?

11 hours ago, Broman said:

But why do both doors have this extra pair in the middle?

"Luggage Belts".

You'll have a matching set of threaded holes on the floor just below the rear interior cover trim.

 

I never cared for the straps. The metal finish was low quality, and they had very limited utility.