Welcome!
This is the first I've seen a 77J without the "Thorsen" marking. I have several non-plated versions that all have "Thorsen" markings.
There was a period in time where Thorsen tools where sold exclusively through one of a few sales outlets; General Tool being one of them. I have Thorsen tools marked with TT in a circle in conjunction with "GT" (General Tool) and other private branding. I suspect these are from the late 20's through early 30's It is possible this is from a period where there was Thorsen production with a private brand (or not branded in this case).
Source – “The Shurtleff and Lawton families: genealogy and history”
Notes E.A Boyd’s Thorsen Tools in San Fran had exclusive rights for northern CA sales; California Tool Co had rights for southern CA., and General Tool Company controlling Washington and Oregon, with “Old Forge” in PA with exclusive rights to the east coast. Notes Thorsen production private branded tools for those distributors. It notes government contracts and “one large contract for wrenches for Indian motorcycles” gave a new lease on life for Thorsen.
link to those 77J ratchet varieties I've surfaced:
http://www.papawswrench.com/vboard/index.php?topic=5307.msg33737#msg33737