For my cowl vent, I got some spacers and plan on drilling the bracket out to fit them and then using a machine screw and nut thru that for the pivot. The original rivet was a shoulder type so there was a spot for it to pivot on and not get too tight. Mine was a bit rusty and needed to be replaced anyway.
My defroster vents came with the clip on one end and screw on the other. The fewer screws needed under the dash, the better.
