Hoping someone here can help.... I have a 1973 Datejust 1603 (SS). I'm looking to swap out the crown to 18k YG. The tube and crown are original to the watch. Crown measures 6mm. What I'm needing to know is... which 6mm crown will fit? I ordered one. Seller didn't realize it was a 5.3mm. He sent another. This one measured 6mm. However, it wouldn't screw down to the tube. Will I have to replace the tube as well? If so, what all do I need to accomplish such a task? Thanks, DJ