Thanks for the info. I have been curious about the grips for a long time and suspected they were not designed specifically for the 66. I might be mistaken about my date of purchase. I bought the 66 used and it is stamped 66-1 ser#115K5**. The checked grips might not have been original to the gun.
I bought a model 66 in the late 70's and it came with an extra set of smooth grips. They fit but seem to be a little different from the stock checkered grips. Does anyone know if these are standard K grips or made to fit another or multiple frame sizes? I will try to attach a photo of the smooth...