I still had some shop time this morning and saw that I could rivet the nutplates into the oil cooler valve plenum - so that's what I did. I first drilled the 4 screw holes out to 5/32" using the #19 bit. After deburring the holes, I put the screw thru the nutplate to line up the screw hole while I drilled the rivets holes for the nutplates. I then used the DRDT to countersink the rivets holes, then riveted the nutplates to the housing. Easy breezy – check that off the list of things to be done.
