You are right about the P&LE car numbers - none were more than 5 digits - and about the ends (1-5-5-5). I checked my Jan 1952 ORER, and there was a NYC series of boxcars 101000-101999 with overall length and height to top of running board dims that are consistent with the dims on the USRA single sheathed cars. Perhaps the P&LE got a donation from NYC's series?
