Very cool old Buck knife your cousin has! Im thinking like others said, its a four strike because the letters are not quite the same height. Group one, my personal favorite due to all the handle variations you see. Buck was making these knives with remnant pieces of lucite he bought from San Diego plastics. They were using whatever looked good i guess. When they started selling through mail order, they had to standardize the handles and thats when we start seeing handles of solid red, green, blue or black, with a thin white stripe in the middle. The sheath does not look original to me but a closer examination might show otherwise. Cant tell for sure but it looks to be a 105 "All purpose knife" or a 104 Camper. Thanks for sharing!!