top wall 42 in fig2 which cooperate to provide center sill pocket 26 supports 44 extend across lower edges 46 and 48 of first and second sidewalls 38 and 40 to provide an essentially closed pocket 26 in center sill 24 to receive draft buff gear apparatus 14 and coupler shank 22 in fig1 and 2 coupler shank 22 in proximity to butt end 30 has a vertical connecting pin bore 50 which is transverse to axis 18 in the figures and about normal to upper surface 32 and lower surface 34 pocket casting 36 is connected to buff draft gear apparatus 14 and shank 22 to provide a moving or sliding connection between these components in fig1 to 4 pocket casting 36 includes chamber 37 and it has upper wall 52 with first passage 54 and lower wall 56 with second passage 58 which passages 54 and 58 are aligned rear wall 60 of pocket casting 36 has an aperture 62 generally centrally aligned with axis 18 pocket casting 36 is positioned and can slide in center sill pocket 26 to receive the rear portion 30 of shank 22 in pocket casting chamber 37 passages 54 and 58 are alignable with pin bore 50 for receipt of vertical connecting pin 64 and connection of coupler 16 with center sill 24 for rotation or pivoting of shank 22 about pin 64 further upper wall 52 and lower wall 56 have inner wall surfaces 66 68 respectively which surfaces slope or are essentially outwardly tapered from passages 54 58 toward open end 70 of center sill 24 pocket casting 36 in the illustrated reference position of fig1 and 2 can slide in cavity 26 along axis 18 however travel of casting 36 in the draft direction is limited by.