Could be a modification to add tilt or an unfamiliar aftermarket manufacturer that made a blade that had the extra feature. The old LeTourneau dozer kits on 30's-40's tractors, there was a tilt/angle dozer, essentially a manual angle and tilt, but a 6 way.
I don't believe the caterpillar dozer kits in that era had tilt, now I could be wrong, but I suspect you are correct, tool bar dozer kits/blades did not or that I can recall, be interesting to see a photo of it if and when you look at it, could be nicely done modification or other manufacturer, interesting question, certainly does not sound familiar for one of these era tractors, could be a blade that someone built for it, I've seen some of those on tractors, just not 6 way. I am trying to recall, but I think Mike Mc over on ACMOC built a nice 6 way for a smaller caterpillar tractor, same era, I remember sending or posting photos of a 6 way on a new D4G I had rented, that was 10 years ago. So, if I recall correctly, its definitely possible, his was nicely done, from scratch, and all hydraulic too.