All you gain with the -3 over the previous examples was the introduction of the "new" yoke retention system, which I happen to prefer, if for no other reason being that the screw is bigger.
You cannot screw it in too deep so as to bind the yoke. The next step in the -4 added the drill-n-tapped holes for scope mounts. Then.....in the opinion of lots of folks....it went down hill from there.
I have a 681-3, which was the last production model for that gun. The 681 was resurrected in some "special" configurations. It looks rather nice in my 4-inch family.
You have a nice quality piece and I could only hope for some of the prices I am hearing. 686 NL's fetch $700 and better where I live.