I was reading the review of the Branchline NYC coach in the latest Model Railroader, and Andy Sperandeo wrote: "As the instructions note, many of the prototype cars rode on four-wheel trucks. Although Branchline isn't offering these yet, the body bolsters have extra kingpin holes for four-wheel trucks."
I'm not a passenger car modeler so that comment left me confused. What's up with that? Why would a car with four-wheel trucks be supported at a different location than one with six-wheel trucks? Is that just specific to the models (perhaps for truck swivel clearances), or was that the case for the prototypes, too?