Actually mine are both D6 bikes that have been upgreded to be D7s. The grip shifters on both were broken and were changed to thumb shifters. The rest of the drivetrains had a lot of wear so it was easier cheaper to get 7 speed parts. They are also both 2002 bikes but were built in to different Dahon plants. Different serial number layout. I have since in the last month seen another Boardwald for $100. More than you wanted to know. Roger