Installs black (1500 lb) on my Tundra 07 4x4. Very easy to assemble without lifting the truck, just loosen the 4 nuts on the U-bolts, pull out the old fender, put the sumo spring back in place and retighten the nuts. Now the truck drives very hard and quite briskly with no load. Haven't used them with any load yet but I expect they will do their intended job of keeping the truck level and minimizing squat. I had assist springs on my other truck and the hard ride is about the same so that's to be expected from this type of product.