QA1 RCK52375 Rear Pro-Coil Single-Adjustable Coilover Conversion Kit GM A-Body 73-77

The QA1 RCK52375 is a bolt-in rear coilover conversion kit engineered for 1973–1977 GM A-Body muscle cars. Designed to replace the factory rear suspension with a fully adjustable coilover system, this Pro-Coil kit delivers a significant upgrade in ride quality, handling, and stance control — with no cutting or welding required for installation.

At the heart of this kit are two single-adjustable Proma Star aluminum shocks featuring 18 positions of simultaneous rebound and compression adjustment, allowing you to fine-tune damping to match your driving style. The fully threaded shock body works in conjunction with the included mounting hardware to provide ride height adjustability, letting you dial in the perfect stance.

The kit includes QA1's American-made high-travel coil springs in a 12-inch length at a 150 lb/in spring rate. These springs are manufactured from high-tensile chrome silicon alloy wire with fewer coils and a smaller wire diameter than conventional springs, resulting in reduced unsprung weight, faster response, and greater suspension travel. All springs are 100% dyno tested and serialized, and are lifetime guaranteed to remain within 2% of their original free height and rate under normal operating conditions.

Kit Includes:

• 2x Single-Adjustable Proma Star aluminum shocks — 18-position simultaneous rebound/compression adjustment
• 2x High-travel coil springs — 12 in. length, 150 lb/in spring rate
• Specially designed USA-made upper and lower mounting brackets
• All necessary installation hardware

Key Features:

• True bolt-in installation — no cutting, drilling, or welding required
• Ride height adjustable via fully threaded shock body
• 100% dyno tested and serialized from the factory
• Rebuildable and revalveable by QA1 or authorized service centers
• Single-adjustable shocks eligible for QA1's Limited Lifetime Warranty (registration required)
• Proudly made in the USA

Spring Specifications:

• Spring Length: 12 inches
• Spring Rate: 150 lbs/in
• Inner Diameter: 2-1/2 inches
• Material: Chrome silicon alloy, silver powder coated
• Ends: Ground and squared for accurate seating

This rear coilover conversion kit is an ideal companion to QA1's front coilover systems, allowing for a complete end-to-end suspension upgrade on your GM A-Body. Suitable for applications ranging from spirited street driving to weekend track use. Note: lower shock mount bracket may not be compatible with aftermarket rear end housings.