Tim,
The only aftermarket OM steel grip frames I'm aware of are those made by Grandmasters Power Custom. They are two piece GFs and will only fit Colt grips. Of course the locating pin could be remounted to fit Ruger XR3 grips and the frame fitted to your grips since they come in the white. They are $200.
You can much easier and cheaper adapt NM XR3 steel grip frames to your guns and grips. Let me know if you want more detail to adapt them like these:
Yes, I would like some more information. I don't necessarily care about OM vs NM as long as I can use the grips I have. The two guns they are going on will be shooters.
Thanks
Tim