2006 GMC Yukon Owner's Manual - Page 68

Third Row Seat - Regular Models For Extended models with third row seating, the top tether anchor is located at the bottom rear of the seat cushion for the center seating position in the third row. Second Row Seat (Bucket Similar) - Extended Models For Regular models with third row seating, there is one top tether anchor located at the bottom rear of the seat cushion that can be used for either the center or passenger side seating position in the third row, but not for both. Never install two top tethers using the same top tether anchor. 1-62