I can't be sure but I don't think I see any gussets welded on the sides of the spring perches. Simply welding the spring perch to the bottom of the frame rail is the standard method on Lippert frames. The spring perch is subject to tearing off the bottom of the frame rails in some cases.
Better frame manufacturers add a gusset that runs up the side of the spring perch and frame rail to attach the two together, prevent side to side twisting, and strengthen the attachment point.