Ill get some pics sent out Monday night. I dont have the rubber backing plate yet, yet to come in from the supply store. The retaining nut is a stepped nut that came with the grinder. The smaller step fits into the hole in the disc perfectly. But the larger step sits on top of the disc about 3/16.
I looked on your site and looked at your pics, it looks like i have the same style of retaining nut. Anyway Ill get those pics sent out Monday. Thanks...Eric