Match spring rate to the weight the truck actually carries, not its empty curb weight. Add up your bumper, winch, skids, drawers, and gear, then choose a spring rated to support that load at proper ride height. Too soft and the truck sags and bottoms out; too stiff and it rides harsh and skips when unloaded. Constant-load builds want a firmer rate than weekend rigs.

Neither is universally better; it depends on the axle and use. Coil springs flex more freely and ride smoother, which favors articulation and comfort, while leaf springs locate the axle and carry heavy loads simply and cheaply. Most modern trucks use coils up front and often out back; traditional pickups and heavy haulers use leaves. Match the spring to how your truck is built and loaded.

Yes — taller progressive or lift-rate springs raise ride height without spacers, and they support the added weight of armor at the same time. That's the advantage over a spacer, which lifts but adds no load capacity. Pair lift springs with correct-length shocks and, past about three inches, control arms. Filter by year, make, and model to get springs valved for your intended height.