Home / Shop / ReadyLift Suspension Leveling Kits 66-3121 Lift, Leaf Spring Block, Rear, 1.0 in., Chevy, GMC, Kit

ReadyLift Suspension Leveling Kits 66-3121 Lift, Leaf Spring Block, Rear, 1.0 in., Chevy, GMC, Kit

SKU: RLS66-3121

Suspension Leveling & Lift Kits

Readylift Suspension

ReadyLift Suspension Leveling Kits 66-3121 Lift, Leaf Spring Block, Rear, 1.0 in., Chevy, GMC, Kit

SKU: RLS66-3121

Suspension Leveling & Lift Kits

BACKORDER This item will be special ordered in for you. Contact us prior to purchase if you require an ETA.

We accept

Description

ReadyLift Suspension leveling kits are the fastest, safest, and least expensive way to level your truck or make room for oversized wheels and tires as large as 37 in. on most full size trucks (varies by vehicle).

Regardless of your suspension, get up to 3 in. of lift without a major hassle or sacrificing ride quality and comfort. ReadyLift thoroughly tests each kit to ensure that your truck will be leveled without overloading or adding excessive strain to any of your factory suspension components.

Additional features of ReadyLift Suspension leveling kits:

* Custom-designed for your specific year, make, and model
* Ideal for eliminating sag caused by a winch, heavy bumper, or plow
* Most kits cost 1/3 less than their competition.
* Fast, simple installation takes about 1/3 the time of other kits
* Steel kits have a durable powdercoated finish
* Aluminum kits are corrosion-resistant
* Coil spring spacers, expertly indexed forged torsion key spacers, and steel tower extensions are available
* Custom, progressive-wound coil springs are offered for specific applications
* Torsion keys have up to a 100 rating on the Rockwell(B) index scale, 25 percent stronger than most OEM torsion keys
* All mounting hardware is included

Note: A wheel alignment is recommended after installation of your new ReadyLift leveling kit.

Part Type

Suspension Leveling & Lift Kits

Data: v4.2 - Upd: 2026-09-29 18:23:54

Specifications

Product Attributes - Brand: ReadyLift Suspension
Product Attributes - Manufacturer's Part Number: 66-3121
Product Attributes - Part Type: Suspension Leveling & Lift Kits
Product Attributes - Product Line: ReadyLift Suspension Leveling Kits
Product Attributes - UPC: 804879374732
Product Attributes - Lift Style: Suspension Leveling Kit
Product Attributes - Primary Rear Lift Component: Leaf spring block
Product Attributes - Front Shocks/Struts Included: No
Product Attributes - Rear Shocks/Struts Included: No
Product Attributes - Brake Lines Included: No
Product Attributes - Hardware Included: Yes
Product Attributes - FMVSS 126 Certification: No
Product Attributes - Quantity: Sold as a kit.
Product Attributes - Notes: Fits models with factory installed Max-Tow package only.

Reference Information

Brand Name/s	Readylift Suspension
StreetFX SKU	rls66-3121
SFX Item ID	5008952
Supplier Item Code	5008952
Manufacturer SKU	66-3121
Manufacturer UPC	804879374732

Compatibility

Application Data

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2024
Ending Year	2012
Engine Type	V8
Liter	6.0
CID	364
CC	5967
Engine Size	6.0L/364
Engine Family	Chevy small block Gen III/IV (LS-based engines)
Drivetrain	RWD
Engine VIN Code	G
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2024
Ending Year	2017
Engine Type	V8
Liter	6.0
CID	364
CC	5967
Engine Size	6.0L/364
Engine Family	Chevy small block Gen III/IV (LS-based engines)
Drivetrain	4WD
Engine VIN Code	Y
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2013
Ending Year	2016
Engine Type	V8
Liter	6.0
CID	364
CC	5967
Engine Size	6.0L/364
Engine Family	Chevy small block Gen III/IV (LS-based engines)
Drivetrain	RWD
Engine VIN Code	B
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	DIESEL

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2014
Ending Year	2016
Engine Type	V8
Liter	6.0
CID	364
CC	5967
Engine Size	6.0L/364
Engine Family	Chevy small block Gen III/IV (LS-based engines)
Drivetrain	4WD
Engine VIN Code	G
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	DIESEL

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2016
Ending Year	2017
Engine Type	V8
Liter	6.0
CID	364
CC	5967
Engine Size	6.0L/364
Engine Family	Chevy small block Gen III/IV (LS-based engines)
Drivetrain	RWD
Engine VIN Code	Y
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2013
Ending Year	2024
Engine Type	V8
Liter	6.0
CID	401
CC	6571
Engine Size	6.6L/401
Engine Family	Chevy small block Gen V
Drivetrain	4WD
Engine VIN Code	B
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2017
Ending Year	2024
Engine Type	V8
Engine Family	Chevy small block Gen V
Drivetrain	RWD
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	DIESEL
Liter	6.6
CID	403
CC	6599
Engine Size	6.6L/403
Engine VIN Code	Y

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2016
Ending Year	2012
Engine Type	V8
Engine Family	DURAMAX V8 DIESEL
Drivetrain	4WD
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	DIESEL
Liter	6.6
CID	403
CC	6599
Engine Size	6.6L/403
Engine VIN Code	L

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2011
Ending Year	2012
Engine Type	V8
Liter	6.6
CID	403
CC	6599
Engine Size	6.6L/403
Engine Family	DURAMAX V8 DIESEL
Drivetrain	RWD
Engine VIN Code	L
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2011
Ending Year	2016
Engine Type	V8
Liter	6.6
CID	403
CC	6599
Engine Size	6.6L/403
Engine Family	DURAMAX V8 DIESEL
Drivetrain	RWD
Engine VIN Code	8
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2016
Ending Year	2017
Engine Type	V8
Liter	6.6
CID	401
CC	6571
Engine Size	6.6L/401
Engine Family	Chevy small block Gen V
Drivetrain	4WD
Engine VIN Code	8
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	DIESEL

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2016
Ending Year	2017
Engine Type	V8
Liter	6.6
CID	401
CC	6571
Engine Size	6.6L/401
Engine Family	Chevy small block Gen V
Drivetrain	4WD
Engine VIN Code	G
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2020
Ending Year	2021
Engine Type	V8
Engine Family	Chevy small block Gen V
Drivetrain	RWD
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS
Liter	6.0
CID	403
CC	6599
Engine Size	6.6L/403
Engine VIN Code	Y

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLE
Beginning Year	2011
Ending Year	2012
Engine Type	V8
Engine Family	Chevy small block Gen V
Drivetrain	4WD
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS
Liter	6.0
CID	364
CC	5967
Engine Size	6.0L/364
Engine VIN Code	L

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLE
Beginning Year	2011
Ending Year	2012
Engine Type	V8
Liter	6.0
CID	364
CC	5967
Engine Size	6.0L/364
Engine Family	Chevy small block Gen III/IV (LS-based engines)
Drivetrain	4WD
Engine VIN Code	L
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLE
Beginning Year	2023
Ending Year	2013
Engine Type	V8
Liter	6.6
CID	401
CC	6571
Engine Size	6.6L/401
Engine Family	Chevy small block Gen III/IV (LS-based engines)
Drivetrain	RWD
Engine VIN Code	7
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2023
Ending Year	2013
Engine Type	V8
Engine Family	DURAMAX V8 DIESEL
Drivetrain	RWD
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	DIESEL
Liter	6.0
CID	364
CC	5967
Engine Size	6.0L/364
Engine VIN Code	Y

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2023
Ending Year	2014
Engine Type	V8
Engine Family	DURAMAX V8 DIESEL
Drivetrain	4WD
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	DIESEL
Liter	6.0
CID	403
CC	6599
Engine Size	6.6L/403
Engine VIN Code	Y

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2023
Ending Year	2014
Engine Type	V8
Engine Family	Chevy small block Gen V
Drivetrain	RWD
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS
Liter	6.0
CID	364
CC	5967
Engine Size	6.0L/364
Engine VIN Code	G

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2020
Ending Year	2014
Engine Type	V8
Engine Family	Chevy small block Gen V
Drivetrain	4WD
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	DIESEL
Liter	6.6
CID	401
CC	6571
Engine Size	6.6L/401
Engine VIN Code	7

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2018
Ending Year	2014
Engine Type	V8
Liter	6.0
CID	364
CC	5967
Engine Size	6.0L/364
Engine Family	Chevy small block Gen III/IV (LS-based engines)
Drivetrain	RWD
Engine VIN Code	L
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2020
Ending Year	2014
Engine Type	V8
Liter	6.0
CID	401
CC	6571
Engine Size	6.6L/401
Engine Family	Chevy small block Gen V
Drivetrain	RWD
Engine VIN Code	8
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2020
Ending Year	2014
Engine Type	V8
Liter	6.0
CID	401
CC	6571
Engine Size	6.6L/401
Engine Family	Chevy small block Gen V
Drivetrain	4WD
Engine VIN Code	7
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	DIESEL

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2013
Ending Year	2014
Engine Type	V8
Engine Family	Chevy small block Gen V
Drivetrain	RWD
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS
Liter	6.0
CID	401
CC	6571
Engine Size	6.6L/401
Engine VIN Code	7

Make	GMC
Model	SIERRA 2500 HD
Submodel	SLT
Beginning Year	2013
Ending Year	2014
Engine Type	V8
Engine Family	Chevy small block Gen V
Drivetrain	4WD
Amount of Lift Front	None
Amount of Lift Rear	1.000 in.
Front Suspension	Independent front suspension
Number of Lugs	8
Fuel Type	GAS
Liter	6.6
CID	403
CC	6599
Engine Size	6.6L/403
Engine VIN Code	B

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ReadyLift Suspension Leveling Kits 66-3121 Lift, Leaf Spring Block, Rear, 1.0 in., Chevy, GMC, Kit

ReadyLift Suspension Leveling Kits 66-3121 Lift, Leaf Spring Block, Rear, 1.0 in., Chevy, GMC, Kit

Description

Part Type

Specifications

Reference Information

Compatibility

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