We have used a lot of Rivnuts, they have a .060 flange that holds the part above the surface, we used a lot to install roof luggage racks. truck mirrors, etc they sometimes will not seat properly if there is any sealer on the underside of the metal It can soften on a hot day and your inserts are then loose. on parts that only require medium torque they work great. I prefer seatbelts anchor plates under the floor and tacked into place or fastened to a sturdy crossmember. The factory repair spec was to use stainless poprivets.to replace defective welds.