I grabbed the closest engines and snapped some pics. The GE's have more room I think?
for some reason? I used the KD 743 short boxed coupler on the GE ES44 that has the most room? First pic.
Second pic is the U28, third pic is another GE with the full sized KD box and the rear cut off.
The SD50 in the last pic has the least of this group. It still fits a full sized KD box with just the rear cut off.