I would agree, the moldboard and cutting edge, and end bits of the blade do look about new. The end bits and that adjacent area can be well worn, and the moldboard of the blade trashed, that one when scoured clean will roll soil nicely.
It looks like a factory built arrangement, I don't recognize it myself, you could post on the Case forum, see if its Case or what have you. The moldboard has adjustable braces for pitch, or it looks to be, nice feature to have when you want to cut more aggressively or less.
The triangular hydraulic lift configuration was popular from the 40's and up, until more modern designs became prevalent. That one looks stout enough for light work, but its not so much the lifting of it, regardless of the way the cylinders are orientated, but more of the forces applied from the blades push arms to the trunnions on each track frame.
Look at a tool bar dozer on an old D2/D4 caterpillar, its triangular but very stout, and its meant to work pushing or pulling.
Straight blades like this are much stronger than 6 way types in regards to pushing stumps and rocks, but all of that force is transferred to the track frames and beyond to the main part of the tractor. An operator needs to be cognizant of that. I have broken a connection on the end of a push arm at the tilt cylinder on a D6D, it was well worn anyways, but when working in rock, even with quite a bit of steel left in the bore/bracket, one good size rock while pushing is all it took.
You said this one did mostly ag drawbar work, odd that the trunnions are worn or broke, more so given the condition of the blade. All of that appears to be rebuildable without complication.
D2 Tool Bar Dozer Images