Thought I would bring this thread back to the top.
Although this is a commercial brass hilted 6" blade Marbles Pilots Knife, it has U.S.M.C. stamped into the hilt. Also, the blade is parkerized rather than blued or bright bladed. This is the only Marbles parkerized 6" blade JPK I have ever seen. This one came out of the Adrian Van Dyk Collection.