Toyota 2006 Tundra Owner's Manual page 154

Center position
1. Remove the head restraint.
'06 TUNDRA_U (L/O 0508)
2. Fold down the cup holder, unfasten
the fastener that attaches the anchor
bracket cover, and lift the cover.
3. Route the top strap through the slot
on top of the seat, pass the strap
through the seat, then latch the hook
onto the anchor bracket.
Close the cover and return the cup
holder to the original position.
2006 TUNDRA from Oct. '06 Prod. (OM34458U)
143