Consider, if you will, these two Bing Swift Reefers:
Reefer #1
...and Reefer #2
At first glance, other than the roof color and the fact the #2 is a bit glossier than #1, there doesn't seem to be much difference. However, notice the doors. Reefer #1 has lithographed wood doors whereas Reefer #2 doesn't. Indeed, the lithography for the doors on #2 gives the impression of steel doors ...and there is more.
If we take a closer look at the doors we see the reporting marks and the numerical ID do not match the #7300 of the Swift car.
so.... if we rummage through the photo files we find the following:
The doors on the Swift reefer are actually the doors for the Bing Pabst reefer sans the litho treatment for wood sided doors. Note the MRTCO designation on the door of the Pabst reefer and the matching M.R.T.X identifier in the bottom corner of the Pabst reefer which indicates these doors belong with the Pabst reefer. So what happened? At this late date it is anyone's guess. Whatever the reason, I rather like the look of the "steel" doors on the second Swift reefer it reminds me of the re-built wood reefers that were a part of everyday life on the real railroads back in the first third of the 20th Century.
