A mounting adapter for mounting a jack to a trailer coupler and/or a trailer frame is described. The mounting adapter may permit the jack to mount to the trailer coupler while retaining both vertical and axial adjustability. The mounting adapter may include a flange and a collar. The flange may include an opening for receiving the jack and at least one mounting aperture for attachment with the trailer frame. The collar may extend outward from the flange and have at least one aperture for attachment with the jack. The collar may also include a rib located for engagement with a slot on the jack. The trailer coupler and frame may include apertures alignable to the mounting apertures, whereby the mounting apertures may permit orientation of the jack to be forward, left, right or rear facing. The mounting adapter may also be vertically adjustable to the jack.