The Peterbilt 378 with a Caterpillar C15 engine is a desirable, durable vocational or long-haul truck often considered the "little brother" to the 379, featuring a shorter 119-inch BBC (bumper-to-back-of-cab) and a fiberglass hood. Commonly found with 6NZ C15 engines (550+ HP) and 13/18-speed transmissions, these trucks are prized for power, though they can suffer from electrical gauge failures.
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Key Specifications & Common Features
Engine: Caterpillar C15 (Pre-ACERT 6NZ or later ACERT models).
Horsepower/Torque: Typically rated between 465 HP and 625 HP.
Transmission: Commonly equipped with Eaton Fuller 10, 13, or 18-speed manuals.
BBC: 119 inches (Short Hood).
Suspension/Rear: Often utilizes Peterbilt Air Leaf or Air Trac suspension with 40,000–44,000 lb rear axles.
Configuration: Popular in both day cab and 70-inch sleeper configurations.
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Common Issues & Considerations
Electrical/Gauges: The 378 is known for instrument cluster, sensor wiring, and gauge failures, often requiring inspection of the wiring harness for corrosion.
Rust: The frame, particularly in northern climates, is prone to rust.
Maintenance: While the C15 is reliable, high-mileage models often have in-frame rebuilds around 1 million miles.
Visibility: Features a shorter, steeper sloping hood than the 379 for better visibility, but retains a classic look.