A knocking over bumps is usually going to be a swaybar link, but a balljoint or tie rod end wouldn't be too surprising. Other things could do it also. In the case of a swaybar link, often you can also get it to knock if you very rapidly steer a short throw left/right/left/right/left/right while driving. For a tie rod, try temporarily sticking an extra unnecessary wheel weight of size about 2 ounces on each wheel (and later remove it) one at a time. If the wheel weight gives you a knock while driving at speed you can expect that a tie rod end is the culprit. You could also jack up the truck at each corner and check for any play/looseness.
Keep in mind that there are a lot of huckster mechanics out there who will sell a steering rack every time they find a loose inner tie rod end. Oftentimes a problem in a steering column intermediate shaft joint (coupler) will be misinterpreted as a bad rack. To tell the difference, you might need someone to rock the steering wheel left/right while you have one hand on the shaft and one on the rack to feel where the vibration is coming from. It also happens from time to time that a steering rack will go bad from wear (although very rarely with Fords) or after a crash.
