My highway patrolman is an S serial number from approximately 1966. What would be the correct stocks to put on it if I can find them? I'm thinking magna grips with the diamond. Is that correct?
It could have been ordered with the higher cost target stocks, sometimes called "Diamond Footballs" (One of the few options offered for the M28). See picture below. I got the picture from this Notable Thread: Smith & Wesson N Frame Stocks / Grips - A Reference Guide
You might want to look through that thread as it contains a lot of good pictures and information.
My 1960 no dash is wearing magnas at the current time. I picked them up in a package deal at a flea market. All I did is use a citrus based wood cleaner on them. Have a set of diamond targets for it also. Bob