Tim O'Connor wrote:
"Arved one of the photos I sent you is a PRR Merchandise Service (not REA express) X29 in Taylor Yard in Los Angeles, incredibly filthy as Tony says, and evidently simply being used as a box car. But that's in the later 1950's, not 1953. LCL was in precipitous decline from 1950 onwards so whole fleets of LCL box cars (NYC, SP, PRR, etc) ended up in general freight service."
This doesn't answer Arved's question and confuses the issue. As you pointed out, this is NOT an express boxcar, and as LCL goes, the Merchandise Service X29s were plain boxcars lacking any special equipment for handling LCL. It's far more likely it was being used as a general service boxcar.
The cars painted in Merchandise Service schemes got incredibly ratty as the years went on, and are definitely a weathering challenge!