I finally got time to pull off the swingarm on my son's DRZ125 and compare it to the 2001 RM80 swingarm I have. They are vastly different and have no chance of swapping. Virtually every dimension except length is different. Unless different year models or the 100 swingarm is vastly different, it would be easier to build from scratch than modify the RM swingarm. DRZem has his work cutout for him. Just an update for any out there considering this.