Shock shopping for a three-quarter-ton is where a lot of money gets spent badly. The parts that look coolest are tuned for going fast in the dirt, and the truck you actually own spends most of its life with 12,000 lb behind it.
Here's how to pick, without the marketing.
What a shock does when you're towing
A spring holds the weight. A shock controls what the spring does next.
Hitch a heavy trailer and you've added weight behind the rear axle, which unloads the front slightly and pre-loads the rear springs. Every input — a bridge joint, a crosswind, a lane change, a semi passing — puts energy into that system. The shock's entire job is to turn that energy into heat and get rid of it.
The failure mode people describe as "porpoising" or "the trailer's pushing me around" is almost always shocks that are done, or shocks that have faded from heat.
Why body diameter is the spec that matters
Damping produces heat. Heat has to go somewhere, and it leaves through the shock body.
A 2.5 in body has roughly 23% more surface area than a 2.0 in body, plus meaningfully more oil volume. More oil means more thermal mass — the same energy raises the temperature less. More surface area means it sheds that heat faster.
Shock fade is oil getting hot enough that its viscosity drops. Damping falls off, the truck starts floating, and the trailer starts steering you. On a long grade with a heavy load, that's exactly the moment you want the shock working.
A bigger body also allows a bigger piston, which means more damping authority at high shaft speeds — the sharp hits, not the slow rolls.
The tiers, in plain terms
| Tier | What it is | Right for |
|---|---|---|
| OE replacement | Twin-tube, minimal oil, no reservoir | Stock truck, light duty, replacing worn factory units |
| 2.0 Performance Series | Monotube, aluminum body, IFP | Stock-height truck that tows regularly — the value pick |
| 2.5 Performance Series | Bigger body, more oil, more authority | Leveled or lifted truck, 35s, heavy towing, mixed dirt |
| 2.5 Performance Elite | Remote reservoir, adjustable damping | The top tier — dual-purpose builds that tow heavy and still get driven hard off-road |
An aluminum monotube beats a steel twin-tube for towing for one reason: aluminum sheds heat far better than steel, and monotube design keeps gas and oil separated so the oil doesn't aerate under sustained work. Aerated oil is foam, and foam doesn't damp.
Picking for how you actually use the truck
Stock height, tows a few times a year, mostly commutes.
2.0 Performance Series. You'll notice the difference over worn factory shocks immediately and you don't need more.
Leveled 2 in, 35s, tows most weekends.
2.5 Performance Series. The extra oil volume matters on long descents, and the bigger piston handles the added unsprung weight of the tires.
Lifted, 37s, dirt and pavement in equal measure.
2.5, and consider the reservoir version if you're doing sustained high-speed rough terrain.
Plow truck or max-capacity commercial.
2.5, and pay just as much attention to your wheel bearings. Front-end load is what's killing that truck.
Clean truck that mostly gets driven on pavement.
2.0 Performance Series. Aluminium monotube damping is a real upgrade over a tired factory twin-tube even at low mileage, and it's the least money you can spend and actually feel the difference.
The part everybody forgets: shock length
If you leveled or lifted the truck, the factory shock is now closer to full extension at ride height. It runs out of travel over dips and tops out with a bang, and topping out repeatedly kills a shock.
Two fixes: a longer shock specced for your lift height, or a shock extension kit that relocates the mount so the stock-length shock works in its designed stroke.
Extensions are cheap and they're the right answer on a mild level. Order shocks in the correct lift range and this takes care of itself.
How to tell your current shocks are done
- The trailer feels like it's steering the truck. Classic rear shock fade.
- Two or three oscillations after a dip. A healthy shock settles in one.
- Cupped tire wear. The tire is bouncing instead of staying planted.
- Wet or oily shock body. Seal's gone, oil's leaving, damping is going with it.
- Nose dive under braking with a load. Front shocks not controlling compression.
- Feels worse hot than cold. That's fade, and it's the one that matters on a mountain grade.
Replace in pairs, and do the ends together
Front pair together, rear pair together, always. Mismatched damping side to side makes a truck feel unpredictable in exactly the situations where you want it predictable.
Front and rear don't have to be done at the same time, but if they have the same miles on them, they're both worn.
Shocks that bolt on
- GM HD 2500/3500 — 2011–2019
- GM HD 2500/3500 — 2020–2026
- Ford Super Duty — 2017–2022
- Ford Super Duty — 2023–2026
We stock Fox 2.0 and 2.5 Performance Series and Performance Elite for GM HD and Super Duty, in the lift ranges that match the leveling kits we sell — so the shock, the height and the geometry actually agree with each other. Pair them with a shock extension kit if you're leveled and the stock mount is leaving the shock near full extension.
Not sure what lift range you're in? Start with how your truck got its height in the first place, then run your year, make and model through the fitment search at the top of the page.
