Use Kadee's #916 coupler. (#1916 if you prefer the smaller coupler size.) This uses the existing Bachmann draft gear; you simply remove the Bachmann coupler head and replace it with the Kadee.
https://kadee.com/htmbord/page916-1916.htm
Later,
K
https://kadee.com/htmbord/page916-1916.htm
Later,
K