Keep hardworking commercial trucks riding smooth with the Monroe Magnum Rear Suspension Shock Absorber 66424, a gas-charged damper built to handle the demands of high-mileage, severe-use class 3-6 trucks and buses. It installs in the rear position as a direct-fit replacement for a range of Kenworth and Peterbilt applications, helping to reduce excessive vibration when you replace worn-out units.
- Nitrogen gas-charged: Maintains tire-to-road contact by reducing aeration and shock fade for quicker response and a stable, more comfortable ride.
- 10-stage valving: Tuned specifically to each vehicle, with a larger 1-3/8-in. bore for more efficient damping control on most applications.
- All-weather fluid: Special additives help with temperature extremes and reduce oil breakdown, while a 2-in. or 2-1/4-in. reserve tube holds more fluid when required.
- Durable build: Shouldered and bonded bushing with sleeve guards against bushing walkout, arc welds up to 360°, and a PTFE-coated bearing with nitrocarburized piston rod support longer service life on most applications.
A robust hydraulic lock-out helps prevent over-extension of air bags, piston top-out and seal damage on most applications, and the design is intended to isolate impact-related noise, vibration and harshness under most driving conditions. Backed by Monroe's 90-day Risk Free Ride Offer and Limited Commercial Warranty. Excessive bounce, poor ride control or increased vibration can be signs your shocks may need replacing — diagnose the cause before replacing.
Fitment (rear): Kenworth T800 (1987-2024), W900 (1981-2024), C500 (1981-2016), K100 (1981-1985), K100E (1985-2003 and 2005-2006), K300 (1993-2005), T2000 (1997-2011), T300 (1995-2008), T400 (1982, 1984 and 1989-1999), T600A (1986-2008); Peterbilt 365 (2008-2012), 367 (2008-2018), 384 (2008-2016), 385 (1996-2007), 386 (2006-2016) and 587 (2011-2016). See the Buyer's Guide tab for engine details and the full application list.
Interchange: HD12140609 · F343375 · F343378 · 85310 · 665906 · K3747 · K37487 · 650404 · M85310 · M89423 · AMS650404 · 57365404 · 0304628 · 0307420 · 410042 · 3919949 · RCSA5310 · SA5310
This part cross-references / interchanges with the following part numbers:
HD12140609, F343375, F343378, 85310, 665906, K3747, K37487, 650404, M85310, M89423, 66424, AMS650404, 57365404, 0304628, 0307420, 410042, 3919949, RCSA5310, SA5310
