Carli CS-FPAP-05 Progressive Add-A-Pack Leaf Springs

Carli CS-FPAP-05 Add-A-Pack for 2005–2007 Powerstroke

The Carli CS-FPAP-05 progressive add-a-pack is built for 2005–2007 Powerstroke trucks that need improved ride quality without losing load capacity. This system replaces the harsh factory overload leaf with a progressive spring pack designed to smooth out suspension movement.

If your truck rides stiff in the rear or reacts harshly over bumps, this upgrade helps correct that behavior.

Replaces the Factory Overload Leaf

The factory overload spring acts like a solid wall. It engages abruptly and causes harsh rebound when the suspension cycles.

Carli removes that lower overload leaf and replaces it with thinner, progressive leaves. As a result, the suspension transitions more smoothly through its travel.

Maintains Load Capacity

This system does not reduce the truck’s ability to carry weight. The main spring pack still determines load capacity.

Because of that, you keep your towing and hauling capability while gaining a more controlled ride.

Improves Ride and Traction

A progressive spring rate allows the suspension to react more predictably. Instead of a sudden hit from the overload spring, the rear end compresses and rebounds in a controlled way.

That change improves:

• Ride quality over medium and large bumps
• Rear tire traction
• Overall stability under load

Built by Deaver Spring

Carli partners with Deaver Spring Manufacturing to produce these packs. Deaver is known for building high-quality spring systems designed for performance and durability.

Important Ride Height Notes

Removing the factory overload leaf can change how the truck sits under load. The rear may sit slightly lower when carrying heavy weight, but the ride quality improves significantly.

Block Requirements for Proper Stance

For 4.5″ Systems:

• Trucks with a 2″ factory block require a 3-5/8″ block
• Ford Part Numbers: 7C3Z-5598-HB, 7C3Z-5598-JB

For 2.5″ Systems:

• Trucks with a 3-5/8″ factory block require a 2″ block
• Ford Part Numbers: 7C3Z-5598-L, 7C3Z-5598-K

Fitment

• 2005–2007 Ford F250 / F350
• 6.0L Powerstroke
• Works with Carli suspension systems

Related Parts (Same Platform)

Complete your suspension setup here:
https://reviewdiesel.com/product-category/6-0l-powerstroke/

Built to Fix Harsh Rear Suspension

Factory overload springs create a rough ride. The Carli CS-FPAP-05 replaces that harsh engagement with a smoother, more predictable suspension feel.