Russell Strodtz wrote:

Obviously a rebuild on the frame of something else. From what can be seen not a very effective job. Usually the RS to RP conversion was done by attaching a vertical unit in one ice bunker. Very similar to a refrigerated trailer or a manufactured housing unit. From the location of the access door they have not only used the ice bunker area but another foot or two of the interior of the car. The old narrow swinging door is another oddity.

Way too much generalization, Russ. Such conversions varied widely, and many were experimental, which helps explain the diversity. It was unusual to replace doors; the idea was to make a quick and cheap conversion to mechanical refrigeration, but obsolescent insulation, the narrow doors you mention, and that useless ice bunker at the other end (if it did not have collapsible bulkheads) really limited how well such cars could perform.
The PFE book has fairly detailed comments on the experiments PFE did, and how they evaluated the results.

Tony Thompson Editor, Signature Press, Berkeley, CA
2906 Forest Ave., Berkeley, CA 94705 www.signaturepress.com
(510) 540-6538; fax, (510) 540-1937; e-mail, thompson@...
Publishers of books on railroad history