QA1 R123-130S Four Link Kit w/ 9" Ford, 64-66 Mustang, Sng. Adj.

Upgrade your classic Mustang’s rear suspension with QA1’s complete 4-link system, featuring a custom QA1 9” rear housing. Designed specifically for 1964–1966 Mustangs, this all-in-one solution delivers modern handling, improved traction, and the strength to handle serious power. Whether you’re building a street-driven restomod or a pro-touring performer, this kit is built to transform how your Mustang drives and feels.

MODERN HANDLING, CLASSIC FIT

QA1’s triangulated 4-link replaces the factory leaf springs with a fully adjustable, geometry-correct rear suspension system. It dramatically improves traction, cornering, and ride quality by eliminating axle wrap and maintaining consistent pinion angle under load. The included QA1 9” rear housing ensures a perfect fit and the durability needed for today’s performance builds.

SINGLE ADJUSTABLE COILOVERS

This kit includes QA1’s single adjustable shocks, offering 18 clicks of combined rebound and compression adjustment. With one knob, you can easily fine-tune ride comfort and performance for your preferred driving style - from smooth street cruising to spirited cornering.

STRONG, RELIABLE, AND READY FOR POWER

The included QA1 9” housing features fully formed trailing arm brackets, a fabricated steel center section, and heavy-duty 3” OD axle tubes. Together, they create a rigid foundation capable of handling up to 800 horsepower. Matched 31-spline alloy axles ensure strength and smooth operation mile after mile.

RIDE HEIGHT & ADJUSTABILITY

Easily dial in your stance with adjustable ride height from factory level to 3” lower. This flexibility lets you fine-tune your Mustang’s appearance and performance without compromising geometry or drivability.

FEATURES & BENEFITS

• Complete 4-link system with QA1 9” Ford rear housing
• Application-specific fit for 1964–1966 Ford Mustangs
• Single adjustable shocks with 18 settings of rebound/compression control
• Adjustable ride height: factory to –3”
• Triangulated 4-link design eliminates axle wrap and wheel hop
• Fabricated center section and 3” OD, ¼” wall axle tubes for maximum strength
• 31-spline 1541H alloy axles rated up to 650 HP; housing rated to 800 HP
• Big Ford “New Style Torino” flanges for easy brake compatibility
• 5x4.5” bolt pattern fits popular Mustang wheel options
• Weld-in installation with self-fixturing brackets for easy alignment
• Made in the USA with premium materials and hardware

EASY INSTALLATION

This kit comes complete with everything you need for a straightforward installation — from the housing and brackets to shocks and hardware. The system uses self-fixturing weld-in brackets that ensure proper geometry and simplify alignment during installation.

Specifications

• Vehicle Position: Rear
• Shock Valving: Single Adjustable
• Springs Included: Yes
• Spring Rate: 130lb/in.
• Axle Shaft Splines: 31
• Width at wheel mount surfaces: 57 3/8in
• Brake Flange: Big Ford "New Style Torino"
• Brake Offset: 2.5"
• Bolt Pattern: 5x4.5 in