The Old Town canoe with serial number 125784 is 18 feet long so my guess is that this is the one with number 125184. It is a 20 foot long, AA (or top) grade, Guide model with mahogany decks, mahogany thwarts, mahogany seats, a keel, a floor rack, sponsons, and rowlocks. It was built between June, 1938 and March, 1940. The original exterior paint color was dark green. It shipped on April 3rd, 1940 to Madison, Wisconsin. A scan showing this build record can be found below.
This scan and several hundred thousand more were created with substantial grants from the Wooden Canoe Heritage Association (WCHA) and others as you probably know well. 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
https://www.woodencanoe.org/about to learn more about the WCHA and
https://www.woodencanoe.org/shop to donate or join.
It is possible that you could have another number or manufacturer if this description doesn't match the canoe. Feel free to reply here if you have any other questions.
Benson