Picked it up today and it's a 66-6. The single action trigger is as good as my PC guns and double action is heavy and mediocre to tapioca. I'll have to work on that.
The photo shows a late production previous generation model 66, as it has a RB and the Smith & Wesson rollmark on the right barrel. It has an older (late '60s to early '80s) pair of Magna stocks.