OK, I grabbed a external retaining ring from the toolbox. The geometry isn't quite what the manufacturer offers so I did a save as and fixed it. Placed the part in my assembly and off I went. Things were going good. Then the next day I reopened my assembly and the old toolbox part was right in the place where I put my altered version. So I replaced the part and again it worked. The very next day it happened again, so how do I replace the part and have it stay that way. Yeah, I tried the save button, but it doesn't seem to matter. What is up with the fastener toolbox that won't allow my assembly to substitute other parts? This is totally annoying at this point, so I want to know or the future that the toolbox stuff can not be altered with out problems. Had I known this would have happened, I would have just started the retaining ring from scratch.