Dedicated merchandise service cars: only home road running?

[OldEastRR]

Cars that were used for things like B&O Sentinel Service, PRR Merchandise, SP Overnights -- the cars specifically painted for that service: did they ever get sent off road? Or were they only for captive use on that specific railroad to run from terminal to terminal? I'm wondering if a foreign road "merchandise car" ever ran in a mail express train of another RR or got sent to their terminal.

[John]

One thing I've learned over the years in this hobby .. there will always be a prototype for everything. Just when someone make a definitive statement .. that never happened, some one will find a picture where it did ..

I would suspect thats the case here

[Bob Bufkin]

Would be rare for those cars to run in express trains.  They were freight cars and are not set up to run passenger train speeds.  Most of them were originally to be used for service on home rails but eventually wound up running just like any other freight car. 

[Spikre]

 
  have read that boxcars with out dimensional data stayed on line[mostly].
  cars that had dimensional data could be run off line,say a PRR car in Florida.
  NYC Pacemaker Service was so popular for a time that regular Brown 40'
  boxcars had "Pacemaker' put on them and were used  in the LCL
  Pacemaker service.later the cars kept the Pacemaker lettering for awhile.
  so this needs pics to confirm or deny depending on the road.
  by about 1960 most LCL business was lost to trucks.
    Spikre