If you are lucky you can knock them out with a punch or chisel [the old nuts ,that is]. I wasted my x-member & the replacment didn't have the nutserts, but I was able to slip nuts thru the holes for the mount using the old masking tape around the nut trick with an offset box wrench. It was a pita but it beat going to town for riv-nuts. What ever you do, DON'T put the bolts down through the crossmember even though it'll be easier. After you flatten the end of the bolt into the nut it'll take a cold chisel to remove your skid plate.