The 5th gen is the current model released for the 2010 model year. The Trail Edition is the only one with a rear locker. The Limited Edition is the only one with full-time 4wd, the trail and SR5 are old school part time units. KDSS is Toyota's hydraulic sway bar system. They have been using in the US since I believe around 2003 on various models. ATRAC is their "active traction control system" which they have been using on various models since around 2001.