I mostly retreated a picture from the 1961 dealer sales flyer I have that shows a lineup of optional accessories.
the accessories are the suburban fender and tool box option, tombstone weight, stepped foot rests, and seat hinge.
I have not seen another seat hinge like this besides the one I own.
The sign I show in my pic is also the hard to find circa 1961 plastic sales and service sign that is also pictured in the same paperwork.