2005 GMC Yukon Owner's Manual - Page 60

If you have an adjustable head restraint, route the top strap under it. Top Strap Anchor Location A child restraint with a top strap should only be used in the second or third row. {CAUTION: Each top tether bracket is designed to anchor only one child restraint. Attaching more than one child restraint to a single bracket could cause the anchor to come loose or even break during a crash. A child or others could be injured if this happens. To help prevent injury to people and damage to your vehicle, attach only one child restraint per bracket. Once you have the top strap anchored, you will be ready to secure the child restraint itself. Tighten the top strap when and as the child restraint manufacturer's instructions say. Yukon XL Second Row Seat (Bucket Seats Similar) 1-54