The 3-D printed coupler mounting brackets on both ends of the B units, and the rear of the A units.
The outer screws hold the coupler to the mounting pad/spacer. The center screw goes all the way through the frame to eliminate the flex of the entire assembly. You could just run the 2 outer screws all the way through the frame and it would do the same thing. The sides of the draft gear box were also ground out to allow maximum swing for the coupler.
The buffer plate had to be cut back or sanded down to the depth of the compressed diaphragms. Otherwise the diaphrams would not compress, causing derailments even on 072 curves. In order to keep them on the rails through the curves coupled this tight, you have to have diaphragms that compress, and maximum swing in the coupler box.
and the fixed pilot... I just ran the coupler moutning screws all the way into the frame.
