Plainly marked G on frame bar. This was normal for this era to mark the grade only on the frame. It has been said that Lefevers with the grade marked on both frame & barrels are all Ithaca assembled guns, though I have some serious doubts on this. There seem to be to many out there marked this way for them all to be Ithaca.
It may well be that this gun was just mis-stamped for grade, it sure looks like an F in all details.

Miller/TN
I Didn't Say Everything I Said, Yogi Berra