The 1988 Marine Corps Marathon was my fist marathon. I needed to break 3:00 to qualify for Boston, and I finished in a little over 2:58. There were well under 10000 finishers that year. I found the results from that year here:
You'll note that the 400th place male came in at 2:59:03. That would have take 124th place overall in 2017, in a field over twice the size.
That's difficult to comprehend