Frank,
"Coke-bottle" is the collectors term for the palm-swell type target stock, the factory never referred to them as such. The first of the oversize "N"-frame target stocks, both smooth and checkered, appeared in 1952-1953 and were generally only used on engraved / special order guns (like tu-tones) until 1956. The earliest lettered pair I'm personally aware of are on an engraved Pre-27 shipped Fall 1952, have a pronounced palm-swell and are detailed in the letter as "Primavera smooth oversize target stocks".
So, to we collectors, there are 'smooth cokes' and that's the way I've heard them described since I started messing w/ S&W's in 1982.
Side note to Larry.. My experience is that 'upgrade' guns in the 1960-up period, with sight options such as yours, most often are also equipped with the 3-T's. Hopefully it will letter w/ all the options, including the smooth stocks.
David