The mystery is solved!

[Northwoods]

Turns out that my Snap-on socket isn't an 86-F.  It's a 36-F.
It's a specialty, a Cam Shaft Nut and Front Bearing Socket for old Fords.
Shows up in the 1923-28 catalog.  No year mark.  And the logo is like none I have seen.  The big S has feet, as they say, and all the letters are in uppercase. 
Big boy; it's 2 9/16" tall.
It's like the largest one in this picture. 

http://s390.photobucket.com/user/snapmom/media/006-4_zps947b222e.jpg.html