Many different replacement grips are available for most Smith & Wesson handguns. Take the pistol to a sporting goods shop (be careful of local laws regarding transporting handguns) to find something which matches.
chec at: midwayusa.com
Call S&W and they will tell you.
Compare it to known examples.
Contact S&W
Standard Catalog of Smith and Wesoon by Supica and Nahas
It's going to take some searching. I would contact several of the places that I have listed on the link below. Or do a search for "air gun parts" on the web
Standard Catalog of Smith and Wesson, 3rd ed.
Check the auction sites.
You must call S&W to find out.
You must call S&W to find out.
You need to find a firearms instructor.
Recommend you find a good gunsmith.