You will want to pick up a Replacement QM3 kit, part # TH04997 . This includes all the pads, bolts, screws and plates to completely replace the mounting hardware.
I went to our warehouse and measured the mounting bracket and screws, and they together measure wide enough to hold a 3-1/2 inch wide by 1-1/2 inch tall ( 88.9mm by 38.1mm) sized Thule Wingbar. view full answer...