This is a special item for enthusiasts. I once considered modifying the F-tubes of Yamaha custom trombones (8420 series, 8425 series, etc.) to a Conn-like wrap, similar to the 648 or 643. I attempted to combine a 648 rotary valve with the joint of an 8425G2. However, I couldn't get new 648 F-tube parts, and the project was abandoned, and my passion cooled. I hope someone will use these parts in my place. These are valuable parts from discontinued models. You could use them to convert the F-tube of a custom series trombone to a Conn wrap, or to change the rotary valve of a 648 or 643 from a string-operated to a ball-joint type. This is truly for enthusiasts. To adapt the string-operated 648 rotary valve to a ball-joint type, I used a Zeno rotary valve base and rotated the damper rubber base 180 degrees, re-drilling screw holes in the rotary casing for installation. The original screw holes were sealed by tightening screws from inside the casing. Please check the 4th and 5th photos. The lever is not included, but I believe a current Zeno lever can be attached without modification. The rotary valve caps are from a Zeno.