Input Requested: Submariner Date ‘Vintage Single Red' 1680

[nbmc5]

All,

Looking for help from this group on a watch I am considering, but a few things don't seem to add up.

Rolex Oyster Perpetual Submariner Date Stainless Steel ‘Vintage Single Red’ 1680

I'm trying to figure out it is listed as a 1978, but I believe the last Red dials were produced in 1975? It appears it is a Mark VI dial and I'm just trying to place the actual year or provenance in case anyone here can help. It looks like the fat font bezel was replaced with a thin font one at some point as well and I can't quite tell if it's been re-lumed or if the pip has been replaced.

Any help appreciated and many thanks in advance.