2½ is a maybe. If you have a stock pitman arm, don't run a drop bracket. Use both together or not at all. When you start getting into tie rod over and axle risers, it still applies. You modify steering and track bar together.
As for it you need it. The stiffer the suspension and the less sensitive the driver is, the less you need it. The softer the suspension and more sensitive the driver the more you want to run one.
There are a couple things going on. One is the aesthetic aspect that a lot of people get tied up in. The axle isn't centered side to side. Simple, as the axle is moved away from the frame the track bar swings in an arc. The greater the vertical distance, the steeper the angle, the more lateral shift. An adjustable (length) track bar can be used to center the axle again. But with so many things there is a trade off. With stock steering you are now not centered in the steering, that is the steering box has uneven travel left to right. Most steering boxes are tightest when on center and have more play off center. Your straight driving is with the steering box off center. You can also run out of travel in the steering box in one direction so you can't turn as tight to the right as you can to the left.
With soft springs there is another oddity. Not truely bumps steer as you can hold the wheel straight, and you drive straight. but bump yaw. The body (and frame) rotate going through dips in the road. The axle goes straight, the track bar swings in its arc, the chassis is pushed sideways. To the left as the suspension compresses, to the right as it extends. There is a very small amount of this in stock form, the track bar nearly horizontal. In a horizontal state there is nearly no lateral shift during normal vertical movement. That is what the drop or lift brackets are trying to achieve again, that horizontal state in normal use.
The steering drag link has to match the track bar. The steering box is giving a movement into the linkage in reference to the frame. What you want is the same movement of the tie rod in reference to the axle tube. Ideally there is no movement in the tie rod to axle as an input from the suspension cycles. For a check you can lock the tie rod to the axle (piece of metal and a few clamps), cycle the suspension and watch for steering wheel movement. Should be none.