"But wait," you say, "Why did you only get 1.5" of lift out of a 3" rear block?" The reason is simple. 4WD F150s come from the factory with 1.5" rear blocks, which are removed when installing a 3" block. Thus, you end up with 1.5" of lift. 2WD F150s don't come with a rear block at all, which is why their equivalent kits are actually 1.5" tall. You can technically put a 4WD 3" lift block on a 2WD truck, but you'd end up with more lift and you'll probably have a rough time finding shocks that can handle it.