@GG1 4877 posted:
The MTH passenger truck on the R50B is the PRR 2D-P5 standard truck that was used for many decades as the standard passenger trucks under the R50s, B60 baggages, and the P70 coaches. They are specific to the PRR.
I read that those trucks were also used on the P58 coaches. Transplanting them onto one of the MTH 70’ Madison coaches could make something slightly more prototypical I guess.