1, 2, and 3 (in circles) are instructions (at lower left) related to parts/located at those circled numbers in the diagram.

The square with 6 inside (next to 3 at the lower left) might be a note-reference (from what Brad posted), but I do not see that note-numberr elsewhere on that page (or associated pages in the 47-55 FAM).

By the way: I have never bent a "bolt lock ear" on my four 1954 GM trucks. Maybe someone else has experience/information about them?