The Old Town with serial number 78521 is a 16 foot long double end boat model in CS (Common Sense or the middle) grade with red Western cedar planking, open spruce gunwales, birch decks, birch thwarts, and birch seats. It was built between May and June, 1923. The original exterior paint color was dark green. It shipped on July 2nd, 1923 to Old Forge, New York. 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 also possible that you could have another number or manufacturer if this description doesn't match. Feel free to reply here if you have any other questions,