This did NOT go well.
Drill your 3/8 inch hole with a proper bit… not whatever bit I used. A punch might be appropriate here too, but I could not find one for 3/8 inch. If you choose to use the 3/4 inch NMO system, there are special drills and punches available to make a clean and neat hole.
Fortunately, this is a 1998 Ford Taurus. A mistake made here would not have been a big deal. However, the 3/8 inch NMO mount did not mind the messy hole. I’m not sure the 3/4 inch NMO would be so forgiving.
