Hellwig 986 EZ-990 Helper Springs for 1999-2007 Silverado/Sierra 1500

Vehicle Fitment

• 1999-2006 Chevrolet Silverado 1500 (All Trims, 2WD/4WD, All Cab Styles, All Engines)
• 1999-2006 GMC Sierra 1500 (All Trims, 2WD/4WD, All Cab Styles, All Engines)
• 2007 Chevrolet Silverado 1500 Classic (2WD/4WD - GMT-800 platform continuation)
• 2007 GMC Sierra 1500 Classic (2WD/4WD - GMT-800 platform continuation)

Fitment Notes

• Fits the GMT-800 generation Chevrolet Silverado 1500 and GMC Sierra 1500 from 1999 through 2006, plus the 2007 Classic continuation models that used the GMT-800 platform alongside the all-new GMT-900 generation.
• Does NOT fit the all-new 2007 Silverado/Sierra 1500 (non-Classic) GMT-900 platform, which uses a different rear leaf spring geometry. Verify that your 2007 truck is the "Classic" (GMT-800) model before ordering.
• Does NOT fit trucks equipped with factory overload springs. If your Silverado or Sierra has factory overload springs as part of the rear leaf pack, those overloads must be removed and discarded before this kit can be installed.
• Compatible with block-style lift kits (blocks mounted under the leaf spring at the axle). NOT compatible with spring lift kits that alter the arch of the factory leaf spring pack, as this changes the geometry required for proper installation.
• Fits all cab styles (Regular Cab, Extended Cab, Crew Cab), all bed lengths, and all trim levels across both 2WD and 4WD configurations.
• Two spring assemblies are included - one per side of the rear axle.

Features

• EZ-990 medium-duty rear helper spring kit engineered for the 1999-2007 GMT-800 generation Chevrolet Silverado 1500 and GMC Sierra 1500, rated at 2,000 lbs. of level load capacity.
• 2,000 lbs. level load carrying capacity - eliminates rear sag during towing and heavy hauling, restoring proper ride height and improving vehicle stability under load.
• Mounts under factory rear axle U-bolt plates - standard EZ-990 bolt-on installation using the heavy-duty U-bolts included in the kit.
• Factory ride completely unaffected when unloaded - the spring engages progressively only as load is applied, leaving the factory empty-vehicle ride character unchanged.
• Reduces leaf spring wrap-up under load, improving rear-end stability, wheel hop resistance, and towing consistency.
• Fully adjustable via heavy-duty U-bolts - tune spring engagement and load response with simple hand tools.
• Adjustable independently per side - accommodate uneven side-to-side loads or asymmetric cargo/trailer tongue weight distribution.
• No drilling required - complete bolt-on installation.
• Hot-formed and heat-treated ASTM 5160 alloy spring steel for maximum strength, shape retention, and long-term resilience.
• Black powdercoated and plated components for corrosion resistance in all weather and work conditions.
• All mounting hardware included - install with common hand tools.
• ISO 9001:2015 certified manufacturing at Hellwig's Visalia, California facility. Made in the USA. Backed by a Lifetime Warranty (for the life of the vehicle).

Specifications

• Part Number: 986
• Series: EZ-990 Medium Duty Helper Spring
• Product Type: Rear Helper Spring Kit
• Level Load Capacity: 2,000 lbs.
• Spring Material: Heat-treated ASTM 5160 alloy spring steel
• Position: Rear axle
• Quantity: 2 spring assemblies (one per side)
• Finish: Black Powdercoated and Plated
• Adjustable: Yes, via heavy-duty U-bolts (independent per side)
• Installation: Bolt-on under factory axle U-bolt plates; no drilling required
• NOTE: Does not fit trucks with factory overload springs
• NOTE: Block lift kits compatible; spring lift kits that alter leaf arch are NOT compatible
• UPC: 745662009861
• Warranty: Lifetime (life of the vehicle)

Included Components

• 2x EZ-990 helper spring leaf assemblies (one driver side, one passenger side, black powdercoated)
• 1x Set of heavy-duty adjustable U-bolts
• 1x Complete plated mounting hardware kit
• 1x Installation instruction sheet

Product Description

The Hellwig 986 EZ-990 Rear Helper Spring Kit is a medium-duty rear load assist kit engineered for the 1999-2007 GMT-800 generation Chevrolet Silverado 1500 and GMC Sierra 1500 in 2WD and 4WD. The GMT-800 platform Silverado and Sierra used a rear leaf spring suspension that, while capable for general use, is prone to rear sag under sustained towing or payload near maximum capacity - a common issue for owners who regularly haul trailers, campers, or heavy bed loads. The 986 increases level load capacity by 2,000 lbs., restoring proper rear ride height and improving loaded handling without any effect on the factory empty-vehicle ride quality.

Installation uses the standard EZ-990 method: the helper springs bolt onto the top of the factory rear leaf packs under the axle U-bolt plates, with the factory U-bolts replaced by the heavy-duty adjustable U-bolts included in the kit. Two important fitment restrictions apply: first, trucks equipped with factory overload springs must have those overloads removed before installation, as the 986 cannot install over them. Second, spring lift kits that alter the arch of the factory leaf spring pack are incompatible - however, block-style lift kits (which add height at the axle pad without modifying the spring arc) are compatible.

The 2007 model year requires special attention: Hellwig's fitment covers the **2007 Silverado/Sierra 1500 Classic** only (the GMT-800 platform continuation) - NOT the all-new 2007 Silverado/Sierra 1500 which launched on the GMT-900 platform and uses a completely different rear leaf spring geometry. Owners of 2007 trucks should verify they have the Classic before ordering. Built at Hellwig's ISO 9001:2015 certified Visalia, California facility and backed by a Lifetime Warranty for the life of the vehicle.