I’m digging the black cylinder and the grips on both. Congrats! I’m going to be the first to say, collecting Smith and Wesson’s is a gateway drug. It starts with the revolvers, then it branches over into the autos. Pretty soon, you wake up one day and have a safe full of them with a conversely empty bank account. You’ve been warned lol.
Your 681 has been refinished , milled or barrel swap , I don't know of any factory 681 PC revolvers or special editions . 681 is fixed sight stainless with full lug barrel, 581 is blued and 686/586 have adjustable sights.