I was so surprised when i checked in here, after many dry checks, and found your message. Thank you.
For the story this plane could have been built at any time prior to 1943, but is not military...doing contract shipping for the military for the Al-can highway. I have a schematic of a DC3 which showed double doors opening at the middle. And, talking to a guy here in Helena MT he said Canadian Mountie's horses were transported by air in built in stalls.
I don't want a beat up old bird. This was a plane from Calgary to Fairbanks with a stop at Fort Nelson to let off the Mountie. The other passenger is Miss America who is going to Alaska to entertain the troops during the second world war. my gmail is franci(dot)mcmahon(at)gmail.com
I would love to hear directly from you. Thanks!