Unsolved Mystery...Pinion Nut size

[badazz81z28]

Ok, I'm baffled! I bought a new pinion yoke and it came with a new nut. The nut that came off the pinion was 7/8" and was removed with a 1-1/4" socket.

I went to install the new nut and its the right thread but too big for the 1-1/4" socket. I went up to 1-5/16" and there was slop. Tried 32mm and too small....tired 33mm and again some slop.

What size is this thing???? I'm so confused!