An X29 is very normal in the case of shipping magazines, storage mail,
etc. to the west coast.
One interesting tidbit I found in the official plans for handling the
Christmas 1945 mail and express rush through St Louis was the fact
that mail going east to NYC MUST be in PRR equipment. To make this
possible (without reloading at Kansas City or points west of St Louis)
the PRR was going to preposition 100 passenger train capable cars on
the west coast.
Jim Murrie

--- In STMFC@... <mailto:STMFC%40yahoogroups.com>, "Al and
Patricia Westerfield" <westerfield@...> wrote:

Watched a 1935 film last night where a guy got off a Santa Fe

passenger train at a station (presumably somewhere near Hollywood).
When it pulled out, there was a Pennsy X29 on an adjoining track.....
Al Westerfield