That's the problem I and possibly every sierra owner have.
The triangle hole is as big as the tutu angle locating peg thing so when you push it through and turn it because the hole us bigger there's about 7 mm play up and down,maybe I am missing something but when you put a bolt and washer through it it only tightens the peg against the bumper bracket,not the wing so the bumper can sag at the sides.
These washers I need will tighten against the wing and pull everything together so I can get an even gap alongside the wing.