Welcome, the Old Town canoe with serial number 175311 is a 16 foot long Otca model with a narrow two and 3/4 inch planking, mahogany decks, keel, and the stern seat moved two inches forward of the usual location. It was built between October and December, 1965. The original exterior paint color was red. It shipped on May 19th, 1966 to Evanston, Illinois. A scan of this build record can be found below.
This scan was 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 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 the canoe. Feel free to reply here if you have any other questions.
The AA grade was discontinued in 1957 and the GS grade only lasted until 1944 as described at http://forums.wcha.org/index.php?threads/15564/ in more detail. My guess is that the stern seat was probably moved forward to improve the feeling of stability. This was done on many canoes during this period as shown at http://forums.wcha.org/index.php?threads/17733/ and elsewhere. Let me know if this doesn't answer your questions.
You are welcome to add pictures, everyone likes that. This is a good place for them. The Canoe Photo Index forum is another option. It is only considered spam if you are trying to sell it, or something else.