KYB KG4012 Shock Absorber - Rear

KYB Gas-a-just Rear Shock Absorber KG4012

The KYB Gas-a-just KG4012 is a monotube rear shock absorber built for trucks and older utility vehicles that need firmer control than a standard twin-tube design. It is a direct-fit suspension shock absorber for select Nissan Frontier, Nissan Pickup, Toyota Pickup, Mazda B-series, Chevrolet LUV, and Toyota Corona rear applications.

Gas-a-just Performance Line

KYB’s Gas-a-just line uses a monotube layout with separate hydraulic and high-pressure gas chambers. That design supports quick response, consistent damping, and reduced fade during repeated suspension movement, which is useful on vehicles that work, tow, or run larger tires and wheels. The KG4012 is part of that performance-focused line and is engineered for rear suspension control on the listed applications.

Key Features

• Adds up to 25% more damping performance over original equipment shocks
• Monotube construction separates gas and oil for fade-resistant operation
• High-pressure nitrogen gas helps improve steering response and suspension control
• Triple chrome plated piston rod helps reduce seal wear
• Designed specifically for truck applications and heavier-duty use
• Dust cover included
• Lower mount type: E1; upper mount type: E1
• Compressed length: 12.91 in; extended length: 20.79 in; stroke length: 7.87 in

Detailed Description

KYB KG4012 is a rear suspension shock absorber engineered for vehicles that need stable damping under load and during repeated road inputs. The monotube design keeps the gas and oil chambers separate, which supports consistent performance and immediate response when the suspension compresses and rebounds. For drivers of a Nissan Frontier rear shock replacement, Nissan D21 rear shock replacement, or Toyota Pickup rear shock upgrade, this part provides a direct-fit solution focused on control and ride consistency.

This part cross-references Monroe Shocks & Struts 911530 for the same application.

What It Helps Address

• Excessive rear bounce after bumps or dips
• Reduced control when carrying cargo or towing
• Shock fade during repeated suspension movement
• Loose rear-end feel on trucks with heavier tires and wheels
• Delayed response from worn OE-style shocks

Installation Notes and Tips

Fits 1998-2001 Nissan Frontier, rear; 1995-1997 Nissan Pickup, rear; 1988-1995 Toyota Pickup, rear; 1986-1994 Nissan D21, rear; 1987-1993 Mazda B2200, rear; 1987-1993 Mazda B2600, rear; 1986-1987 Mazda B2000, rear; 1985-1987 Toyota Pickup, rear; 1984 Toyota Pickup, rear; 1975-1979 Chevrolet LUV, rear; 1972-1978 Toyota Corona, rear; 1973 Toyota Corona, rear; 1970 Toyota Corona, rear; 1967-1969 Toyota Corona, rear.

Verify mount style and dimensions before installation. The listed compressed length, extended length, and stroke length should match the vehicle’s rear suspension requirements. This shock uses E1 upper and lower mounts and includes a dust cover.

Quality Assurance

KYB is known for suspension components engineered to maintain OE-level control characteristics while adding monotube performance benefits. The Gas-a-just design is built to reduce aeration-related fade and support consistent damping in demanding rear suspension applications.