This is a Shimano Crane GS (of the second style with the adjustable cable outer stop) but branded up for Schwinn. I have been told (admittedly by a particularly patriotic American) that Shimano sold more of these gears branded as Le Tour GT300 than they sold branded as Cranes. Certainly the Crane GS established Shimano in the USA as a quality manufacturer, and it is likely that the GT300 Le Tour played a huge part in that.

• Derailleur brands: Schwinn, manufactured by Shimano
• Country: USA, manufactured in Japan
• Date of introduction: 1973
• Date of this example: unknown (no two letter date code, and no ‘333’ marking on pulleys)
• Model no.: GT300
• Weight: 236g
• Maximum cog: 34 teeth
• Total capacity: 34 teeth
• Pulley centre to centre: 75mm
• Index compatibility: friction
• Chain width: 3/32”
• Logic: top normal
• B pivot: sprung
• P pivot: sprung
• Materials: aluminium (including the cable clamp nut!)