The Old Town canoe with serial number 143977 is a 17 foot long, AA (or top) grade, HW (Heavy Water) model with open mahogany gunwales, mahogany decks, mahogany thwarts, mahogany seats, and a keel. It was built between January and April, 1946. The original exterior paint color was dark green. This shipped on April 23rd, 1946 to Branford, Connecticut.
The Old Town canoe with serial number 181406 is an 18 foot long Otca model with a keel and rub rails. It was built between September, 1968 and June, 1972. The original exterior paint design probably looked similar to the one shown at
http://www.wcha.org/catalogs/old-town/designs/design45.gif which was known as the design number 45. It shipped on June 27th, 1972 to Laconia, New Hampshire.
Scans of these build records can be found below. These scans 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
http://www.wcha.org/about-wcha to learn more about the WCHA and
http://www.wcha.org/store/membership to donate or renew.
It is also possible that you could have another number or manufacturer if these descriptions don't match the canoes. Feel free to reply here if you have any other questions,
Benson