Frequently Asked Questions About Peterbilt 357/378 Shock Absorbers

What are the exact year ranges for Peterbilt 357/378 shock absorber compatibility?

Peterbilt 357 models from 1987-2001 and Peterbilt 378 models from 1987-2007 typically use the same shock absorber mounting configurations. However, verify your specific truck's axle configuration, as heavy-duty spec trucks may have different mounting brackets. Check your VIN-specific parts manual or measure your existing shock's extended and compressed lengths before ordering.

What's the difference between standard and heavy-duty shock absorbers for these models?

Standard shocks work well for highway and light-duty applications, while heavy-duty shocks feature larger diameter pistons, thicker mounting hardware, and stronger valving for vocational trucks, off-road use, or heavy loads. Heavy-duty options typically have 1-3/8" to 1-1/2" piston rods compared to 1" on standard models. If you regularly haul maximum loads or drive on rough terrain, heavy-duty shocks will last longer and provide better control.

Can I install these shock absorbers myself, and what tools do I need?

Yes, most experienced DIY mechanics can replace these shocks with basic tools. You'll need jack stands rated for commercial trucks, a floor jack, socket set (typically 3/4" and 7/8"), penetrating oil for rusty bolts, and a torque wrench. Front shocks usually take 30-45 minutes per side, while rear shocks may require removing wheels for access. Always replace shocks in pairs and torque mounting bolts to 150-175 ft-lbs unless otherwise specified.

How do I know when my 357/378 shock absorbers need replacement?

Replace shocks if you notice excessive bouncing after hitting bumps, nose-diving during braking, visible oil leaks on the shock body, or uneven tire wear patterns. Most drivers report needing replacement between 100,000-150,000 miles for standard shocks, though heavy-duty units may last longer. A simple bounce test?pushing down hard on each corner of the truck?can reveal worn shocks if the truck bounces more than once.

Are aftermarket shock absorbers as good as OEM for Peterbilt 357/378 trucks?

Quality aftermarket brands like Gabriel, Monroe, and Bilstein often match or exceed OEM specifications at a lower price point. These manufacturers use the same SAE standards and testing procedures as original equipment. The main differences are usually in warranty coverage and minor valving preferences. Many owner-operators prefer aftermarket options for their better availability and competitive pricing without sacrificing ride quality or longevity.