Hi I was wondering if any one could tell me what year the razorheads were made that are stamped fred bear on one side on pat pending on the other? I have a box of 6 that are and a box of 6 that aren't but the ones that are appear to have a bigger vent looking more like a 56 but they have the flatter tip. I'm curious what dates they are. I can try to post pics if that will help. Thanks