These screw holes are at right angles to the rear cargo bay, on both sides..thinking along the lines of a rear bench seat attachment or another float type fitting?
Thanks!

Fittings for optional child's seat?

MTV

The holes look like they have been used for something at one time. Cargo anchor fitting maybe? Some of the holes line up with the adjacent row of rivets. Could they be missing rivet holes? What thickness of metal is in the hole locations and are they threaded?

Thanks guys!
Good stuff...
ummm.. looks like the rivet line,staring us in the face,that we hadn't noticed.

On my J model, this is where the rear bench seat bracket is screwed down. There are only 2 holes per bracket, tho. The holes are adjacent to the rivet line, not on the rivet line. Perhaps the K model used a beefier 4 hole bracket??