I am repeating myself, but I do believe the Model 10-6 prior to 1968 will have the diamond magna grips as opposed to various other grips mentioned in this thread. There have been some beautiful and valuable grips shown, but the question becomes whether they are correct for the revolver the OP is discussing.

S&W stamped the serial number (without any letters) inside the grip panel up until about 1979. This is a good check for authenticity of the total gun. In other words if the serial number is D908160 then the stamping inside the right grip will be 908160 (made up numbers as an example). It will be across the bottom of the grip panel and upside down with the top of the numbers positioned toward the bottom of the butt. This is not true to all eras of S&W revolvers, but I believe the case for the discussed timeframe of these revolvers (years around 1965 &1966).

Even if the grips do not match due to serial number, it is nice to have them period correct in my personal opinion.