This is interesting. K10 and bowtietim have observed the same thing. When I got my Suburban in 1971, the headliner was tattered and I mostly only had the bows in place.
The bows that attach to the buttons: do they run front-to-back or side-to-side? Do they attach to metal on each end of the bow?
If SI47gmc reads this post: does your GMC have these buttons?