I would appreciate any information on this model or personal experiences that members might have.
According to the Standard Catalog of Smith & Wesson, your 686 was product code #104228, mfg in 1988 for U.S. Customs, 3 inch barrel, round butt, pinned ramp front sight (doesn't mention the width), marked CS-1, dull gray bead blast finish. Doesn't mention total production numbers.
The book says NIB value is $400.00, excellent condition value $325.00, but as I'm sure you know, these values are arbitrary & should be taken with a grain of salt.
Great find, BTW.