I look at this old tractor and see a lot of relations to a Cat D-8H. Looks like they copied a lot from the Cat machine.
Looking at the face of the blade, it is worn down a bit, as you can see the ridges from the inner supports, but it is only patched in the corners, and does not appear to have ever been reskinned. Most Cats as old as this have pushed enough to need the blade skinned a couple of times. That said, with the total disregard for maintenancve that it apparently gets, it is pretty impressive that it has lasted this long.