You may want to get your tape measure out to verify the length of your canoe and take a closer look at the serial numbers on each stem.
The Old Town canoe with serial number 70511 is a 17 foot long, CS grade, Otca model with Western red cedar planking, open spruce gunwales, birch decks, birch trim and a keel. It was built between March and June, 1922. The original exterior paint color was dark green. It shipped on June 29th(?), 1922 to Philadelphia, Pennsylvania.
The Old Town canoe with serial number 170511 is a 16 foot long Otca model with a keel. It was built between October and November, 1960. The original exterior paint color was dark green. It shipped on June 12th, 1961 to Allenwood, New Jersey.
Scans of the build records for these canoes can be found by following the links under the thumbnail images attached below. These scans were created with substantial grants from the Wooden Canoe Heritage Association (WCHA) and others. Additional information about 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 join or contribute to the WCHA so that services like this can continue. See http://www.wcha.org/wcha/
to learn more about the WCHA and http://www.wcha.org/join.html
It is also possible that you could have another number or manufacturer if these descriptions don't match your canoe. Feel free to reply here if you have any other questions.