When and how often has there been changes in Stradivarius stop rod nut design over the years...photos would be nise! Other question is in regards to the valve stem thread size, spring barrel end. New York Strads will fit in loosely in to the modern strads( test mule is a '74) the '74 stem will not fit at all on the NY (B valve) barrel. Does anyone have size and pitch of both. G.