OK I finally got around to pulling out my 8 3/4 from behind a bunch of junk.
It looks as though I was wrong about the bolt pattern. All the measurements added up to an original 8 3/4 out of a a body. Problem was I had purchased a 1976 dart to do a front disk brake conversion, I had removed the spare tire and test fitted it on the 8 3/4 assuming that it was a bbp wheel. As my older brother used to say to me, "see what assumptions do for ya"!
edit now my question is how shall I go about getting this axle adapted for bbp??