There is an article in the S&W Collectors Association Journal about a custom order for ten melonite finished 4566s with lanyards, Briley bushings like the Performance Center guns, slide mounted levers that decocked, but sprang back up instead of staying in the down position, etc. These ten had serial numbers consisting of the buyer's initials (3 letters) followed by a number of the buyer's choice (4 numbers, usually 0001 or the buyer's date of birth).