Ok so my machine shop had this diff laying around, said it belonged to a person who used to race 240z's. That is all the background I have on it.
IT is a 27 spline count with what looks like a key spline, or one large spline. Also I took apart a spare r180 I had and test fit the ring gear and it is almost a perfect match, also the bolt holes match up to the ring gear. Everything about this but the splines scream it is for an r180. Hopefully I will be able to fit it in my 4.11 r180.
Some pics, hopefully you can see the big spline