Anyone have any idea what this hole is for? It is not on all Para butt pads. Is it for a locking rod when in a rack or ?

see the butt pad in this picture.  I apologize for the round about way to get the picture to you but currently photo bucket and I are having a operator headspace error problem.

https://www.google.com/search?q=fal+para+stock&safe=active&sxsrf=ALeKk02r1j3ygEAjMfi4OKfapGfxaVHvCg:1603418382689&source=lnms&tbm=isch&sa=X&ved=2ahUKEwjwjoH5zsnsAhWlY98KHfnnDMkQ_AUoAXoECAcQAw&biw=1317&bih=750#imgrc=vPlPDh83jctgCM

No idea what the hole is for, but here’s the picture.

Attaching a hook for a sling to the butt, maybe?  That's all I can think if.  The FNC version has a loop on the buttplate for that purpose.

Older folding stocks lack the hole.  It came out in the 1970s at the earliest, maybe the 1980s.

This is an original and complete 1963-production FN 50.63/para:

Mattjedi - Thank you for posting the picture for me.

Bigstick61 - my 1981 imported FN 50.63 has the hole.

Thank you for the replies.  Hopefully someone somewhere will give us the answer.

My dad has one of the 1980s 50.63 imports and it, too, has the hole (I think all of those did).  I don't think any 50.63s were imported commercially before the 1980s.  It wouldn't shock me if a handful got imported by private individuals, though, although I've never heard of one.  They first came out in the early 1960s.  The one in the picture I posted is also a "lightweight" 50.63, so the trigger housing, trigger guard, pistol grip nut, stock bolt, and pistol grip stud are all made of hiduminium (an aluminum alloy), as were the magazines normally sent with lightweight models.