Martin,
I've always figured that the short #3 and #4 were built around 1940 (perhaps even in the late 30's), but I didn't have any reliable corroborant evidence for an exact date. Both were short lived in caboose service, having been replaced by the new long cabooses #3 and #4 by 1943. They both sat out of service for a few years until the later-mid '40's when the #3 was converted to sand car service for woods locos until the end of operations and the #4 was renumbered #6 and resumed caboose service with the camp switcher at Camp 44 and Camp 45 until July 1958.
The odd thing is that I have never seen a photo of the short #3 with knuckle couplers. The short #4 photos always seem to have them. When the Swayne equipment arrived in 1940 with knuckle couplers, there were not a sufficient number of long log cars for operations, so for the first couple of seasons with the new long cars, the short log cars continued to operate simultaneously though with separate train units. Perhaps the short #3 only worked with the short log car units with link'n pin until it was removed from service.
Have you seen any photos of short #3 with knuckle couplers? One John Cummings side photo at first seems unclear, but closer examination shows that it had link'n pin. The couplers make me wonder if the short #3 and #4 were built with link'n pin before the arrival of the Swayne equipment and that only the short #4 was converted to knuckle with the arrival of the Swayne equipment. What's odd is that they inspected the Swayne equipment in 1939 and knew they would be getting knuckle couplers. If they were both built with knuckle couplers, it would be highly unlikely that they would have replaced them on the short #3 with link'n pin. (It's just too simple to remove the knuckle and pin a link.)
Thanks,
Tim McCartney
