See the PDF link below for installing body mount coupler boxes, new trucks and wheel sets on Tyco Box cars.
https://images12.fotki.net/v1686/filemC3X/a4014/4/4125954/16375553/RetruckingTycoBoxcars001.pdf (https://images12.fotki.net/v1686/filemC3X/a4014/4/4125954/16375553/RetruckingTycoBoxcars001.pdf)