The blade you posted is what I know as an John Deere 80 blade, also the model 80A blade is very similar with a slightly lighter and wider blade. The OP shows a blade that is unfamiliar to me, don't even think it is a John Deere model. I will try to show a pic of my model 80 blade, I also have an 80A, not sure what is in the pic.That's the older style 80 blade. I have one out back that I gave $200 for 35 years ago (used) when we bought this property.
That is the 80A blade mounted on my model 80 blade frame. Now are we all confused, model 80 blades are hard to find that are in usable condition.