but gotta remember there are little 'other' changes that also come into play such as the locating pin being moved slightly on the new XR-3 (ie the flatop anniversaries) versus the "old" and the frame at the top of some of the "new" NEW models does NOT have that angled support, cast into the upper corner...'older' Ruger grips need the cut out (slant) and the top front corners, where some of the newer ,NEW models don;t have this, so the grips dont need the cutout..........
we see folks at the gun shows and in gun shops trying to figure out just what grips their gun needs, we tell them to bring in the gun, and gotta try 'em, see just what frame they do have on their gun...must remember lots of Ruger folks over the past 50 plus years, have also swapped out their grips frames for 'others', so the answers are NOT cut and dry,nor serial number related....as flatgate notes, remove your grip panels and read what the casting number says,thats a GOOD start.