COHgirl, I found this, which looks authentic to me, for comparison: http://morninggloriousvintage.com/Listings%20Purses%20Accessories/Purse_Coach_BrownLeatherMessenger_SWL-2.html
There's also this one (a bag that's claimed to be from the 70's). Its creed more closely resembles the one you're concerned about: https://shop.marketpublique.com/item.php?id=1672
They're both genuine but neither are from the 70s. The top one is from 1995 and the second from about 5 years before that, give or take a year either way. The creed on the fake black one doesn't resemble any genuine bag I've seen, they didn't even get the Coach logo right..