The Old Town canoe with serial number 180662 is a 17 foot long Otca model with half ribs and a keel. It was built between April and May, 1968. The original exterior paint color was pale blue. It shipped on May 29th, 1968 to Portland, Oregon. A scan showing this build record can be found by following the link at the attached thumbnail image 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/ot_records/ if you want more details. I hope that you will join or renew your membership to the WCHA so that services like this can continue. See http://www.wcha.org/about-the-wcha/ to learn more about the WCHA and http://store.wcha.org/WCHA-New-Membership.html 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.