Rockrivr1, That is a well preserved example. I bought a new MK III Trooper in about '73. Only gripe I had with mine was the very heavy DA trigger pull, compared to the S&Ws I was used to.
I had a Government model Colt with the electroless nickel finish, and a Combat Commander with the satin nickel finish. The finish on your MK III Trooper sure looks like the electroless nickel finish, at least as it appears on my monitor. The Colt satin nickel /"satin chrome" ?, finish was a much more coarse, almost sand blasted looking finish.