That's really interesting Jason, I can relate to your fathoming, since for many years being so far away had to do same. I only have the two printed rosters to go by, there may be other written records that I am unaware of. You could plumb Rick Steele and Derrell Poole since they are the foremost authorities on this stuff, or you could ask in this thread on the same cars. [
c-sng-discussion-forum.41377.n7.nabble.com] Harry Brunk did write extensively on the C&S freightcar fleet in his NG&SL Gazette series.
There was to my understanding several revisions to the C&S fleet, whether these applied to the Ph-1 like #4319 I cannot state, even to if these were built with Automatic Couplers or Selden Couplers. There has been mention of revisions to the Safety Appliances and a general overhaul of the fleet at another time. Again I cannot state whether these applied to the #4319.
The only thing I can offer is the Trucks at some time could have been rolled out during said overhaul, one bad wheelset replaced and those not necessarily replaced back under the same car, perhaps. I can only relate to that being a possibility not state it as fact, since I know little of C&S shop practices and capabilities. General programs would dictate a work flow practice rather than complete start and put back together one on one examples such as what the Friends do per car at the C&TS. There has also been mention of the shopping of the Cars for use in the 1936 heavy traffic rush to Climax.
One last thing that comes to mind is the #4319 Car was selected for donation to C.C. and was tidied up, were the Trucks swapped out at that time?
I'll follow your quest with interest.