Jim, I guess I need to provide some more pictures. I just received the gun and have not cleaned or fired it.
It is stamped Mod. 16 in the yoke below the serial number.
The back of the extractor star is not stamped.
It came with these football cutout target stocks. They have blue washers and no SN stamped inside.
I'm not sure about sending it to S&W for refurbishment. I'll talk to Bob Cogan about it in the near future after Irma. APWCogan is a secondary manufacturing facility for S&W, Ruger, and Colt. If it can be restored, I'm sure he can do it. I'm still not certain the muzzle can be saved.
One good thing is the sight base picture looks worse than it is. I think some light polishing will remove the corrosion and not require a replacement.