2019-2024 GM 1500 Trail Boss / AT4 4" Big Lift Kit w/ Falcon 2.1 Shocks (44-39421)

Description

ReadyLIFT's reengineered 4" Big Lift Kit for the 2019-2024 Chevy Silverado 1500 Trail Boss and GMC Sierra 1500 AT4 adds 4" on top of the factory 2" lift. The engineering updates developed for the 2025 trucks carry over: redesigned steering knuckles for a better turning radius, retained factory Auto 4WD and revised geometry to help prevent driveline vibration, and it now ships with Falcon 2.1 Monotube rear shocks.

Part Number: 44-39421 (supersedes 44-39420)

Features

• Falcon 2.1 Monotube extended-length rear shocks (2.3" aluminum body, 3/4" shaft)
• Redesigned steering knuckles for an improved turning radius
• Retains factory Auto 4WD functionality
• Revised suspension geometry helps prevent driveline vibration
• Includes ReadyGuard Powertrain Warranty

Tire Fitment:

• *Max with trimming: 20x10 -18 offset - 35x12.50 or 325/60R20

Notes

• Use of Auto 4 Hi feature not recommended
• Not compatible with rear mono-leaf springs
• Single Cab configuration has not been validated for fitment & drivability by ReadyLIFT
• Not for use on diesel applications (no oil line relocation bracket included)
• 18" wheels are not recommended; an 18x9 with 0mm offset or higher does not fit
• Late 2024 trucks with round rear U-bolts require U-bolt kit 67-35150UB