The only advantage of a SunTour VGT over a Sun Tour 7-GT is lower weight. They both used the same geometry and had the same chain wrap capacity and large cog limit. The 7-GT was basically a more economical version of the VGT, using more steel to reduce the cost but at a 85g weight penalty.


As to whether the 7-GT is original to the bicycle, there is a small possibility. The 7-GT was released for the 1976 model year. Consequently, SunTour would have started building the early production units just around the same time as the subject frame. However, the frame manufacturers typically wouldn't start building their new models until around September and it seems unlikly that Kuwahara would install a 1976 model year derailleur on what should be a 1975 model year frame.


By examining the relative manufacturing dates of the frame and derailleur, we will have a better idea of the probability of the derailleur being OEM to the bicycle.There will be a date code on the derailleur. It will consist of two letters (often within a circle) and is typically located on the back of the inner parallelogram arm. Attached is an example with a WH date code. The SunTour date code key can be found at Date of Manufacture of Bicycle Components can be used to date a bike: component dating