The Old Town canoe with serial number 43531 is a 17 foot long, CS (common sense or middle) grade, Otca model with open spruce gunwales, ash decks, ash thwarts, ash seats, and a keel. It was built between June, 1916 and March, 1917. The original exterior paint color was battleship gray. It shipped on April 11th, 1917 to Cleveland, Ohio. A scan showing this build record can be found by following the link behind the thumbnail image attached below.
This scan and several hundred thousand more were created with substantial grants from the Wooden Canoe Heritage Association (WCHA) and others. A description of the project to preserve these records is available at
http://www.wcha.org/catalogs/old-town/records/ if you want more details. I hope that you will donate, join or renew your membership to the WCHA so that services like this can continue. See
http://www.wcha.org/about-wcha to learn more about the WCHA and
http://www.wcha.org/store/membership to join.
It is also possible that you could have another number or manufacturer if this description doesn't match your canoe. Feel free to reply here if you have any other questions,
Benson