You said the guy sold you a 107.That sounds like you have it in hand .Just put everything together nice and clean and carefull and see if it works.If it does,take it apart ,grease it and put it together for good.If it doesn't,return the 107 and get a 103.I don't get why so many people come here asking about s**t the already own instead of just measureing it(like what size is my seatpost) or just putting it together.