I have Kadee #710 and #711 'old time' couplers on MY 'Oldtime' cars.
Not that there aren't other meritorious approaches ... but to quote engineering terminology. it's about 'form, fit. and function'.
http://www.kadee.com/htmbord/page63.htm
http://www.pacificcoastairlinerr.com/1905/freight_couplers/
Thank you if you visitHarold