Bring firm, gas-charged damping back to the rear axle of your heavy-duty Peterbilt with the Monroe Magnum Suspension Shock Absorber 65400 — a rear-position shock built for the demands of high-mileage, severe-use class 6-8 trucks and buses. It's the first gas-charged, large-bore shock designed for air spring and taper leaf suspensions, and its nitrogen gas charge provides the fast response heavy-duty truck suspensions rely on. It's a direct-fit rear replacement for a wide range of Peterbilt models, including the 357 (1986-2008), 362 (1981-2006), 377 (1987-2001), 378 (1988-2007), 379 (1986-2007), 384 (2008-2016) and 386 (2006-2016) — see the "Vehicles it fits" section for the full list.
- All-weather fluid: special additives help handle extreme temperatures and reduce oil breakdown, while a larger 2-3/8-in. reserve tube holds more fluid (most applications).
- 10-stage valving: tuned to each vehicle and paired with a larger 1-3/4-in. bore for more efficient damping control and a smooth ride (most applications).
- Strong and durable: a shouldered bushing plus a bonded bushing with sleeve protect against bushing walkout, with arc welds up to 360°.
- Hydraulic lock-out: a robust lock-out helps prevent over-extension of the air bags, piston top-out and seal damage (most applications).
A PTFE-coated bearing reduces friction between the rod and rod guide, and a nitrocarburized piston rod adds durability and longer service life (most applications). The nitrogen gas charge helps maintain tire-to-road contact by reducing aeration and shock fade, and the design isolates impact-related noise, vibration and harshness under most driving conditions. Backed by Monroe's 90-day Risk Free Ride Offer and Limited Commercial Warranty.
Interchange: ABPN32G900039 · ABPN32O900039 · HD12150037 · 44185033 · F346598 · 85033 · 89427 · 341620 · 0306085PLUS · 650400 · M85033 · M89427 · AMS650400 · 57365400 · 0306084 · 0307423 · 665633 · 0305384 · 315549 · 3919946 · SA5033
Product information is for general reference and may contain errors. See our Disclaimer.
This part cross-references / interchanges with the following part numbers:
ABPN32G900039, ABPN32O900039, HD12150037, 44185033, F346598, 85033, 89427, AMS650400, 341620, 0306085PLUS, 650400, M85033, M89427, 65400, 57365400, 0306084, 0307423, 665633, 0305384, 315549, 3919946, SA5033
Frequently Asked Questions
Where is the Monroe Magnum 65400 installed?
It's a rear suspension shock absorber for class 6-8 Peterbilt trucks and buses. Confirm your model and year against the "Vehicles it fits" section before ordering.
Which vehicles does it fit?
Rear applications on Peterbilt models including the 330, 357, 362, 372, 375, 376, 377, 378, 379, 384, 385, 386, 387 and 587 across various years — see the "Vehicles it fits" section for the full list.
What makes the Magnum shock suited to heavy-duty trucks?
It's a gas-charged, large-bore shock for air spring and taper leaf suspensions; the nitrogen charge provides fast response for class 6-8 truck and bus suspensions.
How does it affect ride quality?
10-stage valving tuned to each vehicle and a larger bore provide efficient damping, while the nitrogen charge helps maintain tire-to-road contact by reducing aeration and shock fade (most applications).
Is it sold individually?
This listing is for one shock absorber. For balanced handling, it's best to replace the shocks on the same axle together as a matched pair.
