There are now three 3-D printed body mount “CamPac” coupler boxes that accept Kadee centerset, no offset, couplers (available via Colin Camarillo’s website) for the following 1/29 G scale items:
(1) The Aristo-Craft U25B locomotive - t**hat’s also more prototypically lowered whilst correcting for its notorious leaning tendency
See “Installation Guide for Aristo-Craft U25B & CamPac Components” (It’s worthwhile to see this guide if only to see how things fit and can be taken apart)
(2) The American Main Line (AML) Bethgon Coal Car
See “AML Bethgon Car CamPac Box Quick Install Guide”
(3) The USA Trains Heavyweight Passenger Car
See “USA Trains Heavyweight Passenger Car CamPac Box Install Guide”
-Ted