Combine included in MTH 20-4118 PRR Madison 2-car passenger set? Help.

Here are photos of prototype Madison style RPO cars. Notice the full width baggage door at one end.

The "shorty Sante Fe" car that you picture is certainly not an RPO.  It may have had a locked express section but was not worked by postal workers enroute.  The Pennsy car you show is a standard "combine" car.  pro hobby's photos do show a typical RPO, with one end as an express car.  That style of car did carry postal workers who would sort mail enroute.

Paul Fischer

Here is a later version of an MTH Madison combine.  Notice that this has a different body style that includes a side door with step.  This is from set 20-4158.