There are no threaded inserts in the door shell, behind the door panel, but there are two sets of square holes, in the door shell. A pair for the forward position and a pair for the rear position. Either position, requires a pair of spring nuts, which are square nuts with a capture spring on two edges, that hold them in the square hole, from the backside of the door shell. You can get them from the yellow bins of most of the large box stores, like Lowe's & The Home Depot.
