I've never seen this date stamp, and I'm always learning new stuff. Where is it located? I'm guess it's Fisher Body stamp. I've seen different versions of the luggage rack, not sure if it's correct. Comments appreciated.
https://www.ebay.com/itm/255654899654?hash=item3b86382fc6:g:BeUAAOSwPeNivxRM&mkcid=1&mkrid=711-53200-19255-0&siteid=0&campid=5337538513&customid=&toolid=10001&mkevt=1
Subframe Date Stamp, Ink, Stencil or Stamp? Generally located outboard facing, Pass or Driver side. My 69 (LOS) is stamped and it is located on Driver Side Front very near the Bumper support Holes, Others might note other locations/examples.