Who sold your son the BP-51 kit? There is a certain amount of vendor culpability when they are selling a product build for X for vehicle Y. It is true that ARB doesn't have any application for the GX470, that of course doesn't mean there isn't parts and components that fit and can be tweaked to fit, but it does mean the manufacture can be a little less liberal about warranties and the vendor could and should be the front line of defense long before your son contacted ARB direct, it should have been a non-issue if his vendor took care of it imo.
Thx Kurt. I guess its more complicated than I thought. He bought a GX470 with the susp installed. Had been on the GX 6mos. Purchased from Slee Offroad who told him to contact ARB. Its an eye-opener to see ARB do the dance and not stand behind their products. He will be trashing the OME susp and moving on to a company that has support and stands behind their products. Lesson learned. ARB lost a customer for life.