I have never heard of a 66 with a full lug barrel, and that barrel looks just like a 686 barrel. If that was done as a factory special it would be pretty much a 1 of a kind and would be priced accordingly. Unless you personally know the seller and their character I would take what he says with a grain of salt. upon closer examination of the pictures, I see that the barrel is pinned and it looks like the cylinder is recessed. The 686 never had either of these features. I don't know if you can put a newer styled non-pinned barrel into a frame made for a pinned barrel. The 66-1 ran from 1977 until the dash 2 came out in 1982. A very late dash 1 would have been in the factory about the same time as the first 686's were being produced. If the serial number is very late in the dash 1 series, I suppose its possible it was made that way. If its serial number is from 77 to about 1979, I would say there is no chance it is factory original, because they would not have had any full lug stainless barrels, and I doubt they would design, test and manufacture a whole new barrel just for a gun or 2 Is there a box included that would be marked in a manner to denote a special order? If not, the only way to find out for sure is a factory letter from the Historical foundation. If I were the seller, I would want that to prove the original configuration and so I could get top dollar for a one of a kind factory special made gun
