6" (6-inch + Factory 2-inch) Big Lift Kit With 2.1 Falcon Shocks - 2019-2024 1500 Trail Boss / AT4 (part number 44-39621).

The 44-39621 lift kit utilizes the very best in ReadyLIFT engineering with boxed steel front/rear cross members and a full-width front skid plate constructed of thick 3/16" plate steel. New 1/4-inch boxed plate steel differential drop brackets feature a double gusset and boxed center rib to take the abuse of front differential torsional twisting. Our 6" (6" + 2") lift kit features heavy-duty angled and offset top mount strut extensions that realign the struts to optimize shock performance and minimize wear.

A specially designed lower mount strut pre-load spacer offers the added benefit of a slight increase in spring rate to better handle the larger wheels and tires that will find their way onto this new lifted truck. To lift the rear, new fabricated steel rear blocks with integrated bump stop landings have been added as well as new rear Falcon 2.1 Monotube shocks.

Thousands of miles of road and trail testing have proven our new 6" lift kit makes these new GM 1500 trucks ride better than stock! Maintains the factory ride and handling. The proprietary lower strut clamshell design maintains factory geometry and retains the use of the factory strut. Tube steel upper control arms with maintenance-free pivot bushings and 1-ton ball joints. 3/16-inch thick steel plate cross members and skid plate. Anti-torsion boxed and gusseted plate steel differential drop brackets.

Fabricated steel 5" rear lift blocks include integrated bump stop landings, offset pin, and provide proper pinon angle. Also includes rear add-a-leaf for additional 1.5" lift. Includes premium Falcon 2.1 Monotube extended-length rear shocks. Includes ReadyGuard Powertrain Warranty.

Fitment and Installation Notes

• Delivers clearance for increased aftermarket tire sizes - up to 37x12.50 on 6-inch kit on 9" wide wheels with 0 offsets with no trimming. -18 offset will require minor trimming.
• Use of Auto 4 Hi feature not recommended.
• Not compatible with rear mono-leaf springs.
• Not for use on Diesel as we don't include an oil line relocation bracket. Click here to learn how to determine if you have rear mono-leaf springs. Single Cab configuration has not been validated for fitment & drivability by ReadyLIFT.
• Not for use on Diesel motor applications.
• These will not fit late model 2024 or 2025 applications that have round U-bolts. Using U-bolt part number67-35150UB will allow this kit to fit 2025 applications.

Additional Product Details

Falcon Shocks - The Ultimate Blend of Performance, Quality, and Value

• Falcon 2.1 Monotube Shocks deliver increased stability, improved ride quality, and enhanced comfort in a compact, high-value performance package.
• Optimized for on-road driving, Falcon 2.1 shocks provide increased stability over stock while maintaining confident performance both on and off the road.
• Vehicle-specific damping makes Falcon 2.1 shocks ideal for daily-driven trucks and SUVs, as well as enthusiasts looking for a consistent, controlled feel across a variety of driving conditions.
• Race-inspired technology delivers improved handling, stability, and chassis control for lifted trucks, SUVs, and off-road vehicles.

Falcon 2.1 Monotube Shock Specifications

• Large 2.3-inch shock body for increased oil capacity, improved heat dissipation, and consistent damping performance
• 6061-T6 aluminum-alloy billet piston
• Heavy-duty 3/4-inch induction-hardened, chrome-plated shaft designed to resist rock damage, corrosion, and shaft buckling
• Microcellular foam progressive bump stops*

*Bump-stop configuration varies depending on shock absorber collapsed length, tire size, and fender clearance.

Recommended max tire with no trimming: 20x9 0 offset - 37x12.50 tire.

*Max with trimming: 20x10 -18 offset - 37x12.50.

Trimming requirements for larger than recommended wheel/tire include front valance, front felt liner edge, rear felt liner edge and front rear well edge mud flap.

Tire Size Note: ReadyLIFT wheel and tire fitment recommendations are typically based on Wheel Pros wheels and Nitto tires. Due to product differences among tire manufacturers, tire specifications and dimensions including, but limited to, overall diameter, rolling diameter, tread width, aspect ratio, lug pattern, sidewall construction and inflation pressure, will vary meaningfully by tire and wheel manufacturer. Every tire and wheel combination should be test fit prior to installation. Consult your local installer to learn more about the right tire fitment for your application.

Ride Quality Note: When lifting a vehicle and installing aftermarket wheels and tires, a tire manufacturer's construction and material quality can alter vehicle ride quality. When increasing a vehicle wheel and tire size, most larger aftermarket truck and SUV tires are 10-ply (or more) E tires compared to typical OEM 6-ply C tires. This more rigid sidewall construction increases the perception of suspension stiffness often described as ride harshness. The ride, handling, traction, noise, fuel economy, and wear differences between All-Season, All-Terrain, Mud-Terrain, or Trail-Terrain type tires can be significant. Please take into account tire and wheel choice will generally have a meaningful impact on the ride & handling experience.

Heavy-duty front-rear cross members and skid plate

Heavy-duty top mount strut extensions and rear shock extensions

Sway bar drop brackets

Heavy-duty fab steel rear lift blocks with bump stop landings.

Heavy-duty cast iron lift knuckles engineered to retain factory quality geometry.

All necessary hardware and instructions.