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Engine/Drivetrain

Heavy-Duty Engine & Drivetrain Parts for Semi Trucks

When power, torque, and reliability matter, the engine and drivetrain sit at the heart of every working rig. These systems do the real work, converting fuel into motion and transferring power from the engine to the wheels without hesitation. At Fitzgerald Truck Parts, we supply a full lineup of semi truck engine components and drivetrain solutions built for hard miles, heavy loads, and long-haul performance. 

We offer a wide range of critical parts, including semi truck engine parts, semi truck drivetrain parts, transmissions, mounts, seals, bearings, turbochargers, gaskets, and supporting hardware. Our stock includes OEM and high-quality aftermarket options from trusted manufacturers such as Cummins, Caterpillar, Detroit Diesel, Eaton, Jacobs, Fleetguard, Alliance, and Paccar. Each part is selected for durability, precise fitment, and real-world performance, making them a solid choice for owner-operators and fleet managers who demand dependable results from their equipment.

Keep Your Truck Running Strong

Routine maintenance and timely replacement of worn parts help protect uptime and control operating costs. By replacing aging truck engine components and truck drivetrain components, you support your rig's optimal fuel efficiency while also reducing stress on connected systems and helping avoid breakdowns that can pull trucks off the road at the worst time.

We supply on the top heavy-duty truck engine parts and heavy-duty drivetrain parts, and each one engineered to meet or exceed OEM specifications. These components are built to handle high temperatures, extreme pressure, and constant vibration, all while delivering consistent power and smooth operation across long distances.

Our inventory supports major engine platforms with a strong selection of Cummins engine parts and Detroit Diesel engine parts, along with components designed for popular transmission setups. For repairs requiring deeper service, we carry truck transmission parts and complete engine rebuild kits that give shops and drivers the ability to restore performance without unnecessary guesswork. For full replacements, our selection of Reman Engines delivers tested performance ready for immediate installation.

We also stock essential diesel engine components that support lubrication, airflow, and electronic control systems. Popular subcategories include: 

We're proud to deliver parts that can keep heavy-duty trucks pulling strong mile after mile. Plus, with fast shipping, easy online ordering, and knowledgeable support, we make it easier to source the right parts and keep trucks earning. 

Semi Truck Engine Component FAQs

What parts are included in the engine and drivetrain category?
This category includes truck engines, transmissions, rebuild kits, bearings, seals, turbochargers, gaskets, and other essential powertrain components used to maintain and restore truck performance.

Which brands do you carry for engine and drivetrain parts?
We stock parts from leading manufacturers such as Cummins, Caterpillar, Detroit Diesel, Eaton, Paccar, Jacobs, and Fleetguard.

Are the parts OEM or aftermarket?
We carry both OEM and high-quality aftermarket parts to support different repair needs and budget ranges.

How can I find the right part for my truck?
Search by part number, brand, or truck make and model. Our support team is available to help verify fitment so you order the correct component the first time.

  • Regulator Housing Gasket

    PAI Truck Parts

    Regulator Housing Gasket

    Regulator Housing GasketCaterpillar 3400 / 3406E / C15 / C16 / C18 Series Year/Make/Model: Year Make Model All CATERPILLAR 3406E SERIES All CATERPILLAR C15 ENGINE All CATERPILLAR C16 ENGINES All CATERPILLAR C18 ENGINE All CATERPILLAR 3400...

    $3.40
  • Upper Gasket Kit

    PAI Truck Parts

    Upper Gasket Kit

    Upper Gasket Set Upper Gasket SetEGR enginesCummins ISX Series application Consists of the following:ECM Gasket Kit Turbo Gasket Kit Front Structure Gasket Kit Cooling Gasket Kit Head Gasket  Fuel Gasket Kit   Replaces OEM Part...

    $435.43
  • Flywheel Housing,  ISX CUMMINS, 3103584, 3680063

    PAI Truck Parts

    Flywheel Housing, ISX CUMMINS, 3103584, 3680063

    FLYWHEEL HOUSING, ISX CUMMINS, 3103584, 3680063 Flywheel HousingCummins Engine ISX Series Application Durable construction Direct replacement for OE part 3680063 Cummins ISX Series Engine Application

    $726.53
  • Camshaft Bearing

    PAI Truck Parts

    Camshaft Bearing

    CAMSHAFT BEARING OEM: 3945329 Camshaft BearingRequires 7 per applicationCummins 6C / ISC / ISL Engine application

    $5.89
  • Tappett

    PAI Truck Parts

    Tappett

    TAPPET OEM: 3925031 2.36in LengthCummins 4B/6C/6B/ISC/ISL/ Application

    $5.81
  • Oil Pump Kit

    PAI Truck Parts

    Oil Pump Kit

    Oil Pump KitCummins 6C / ISC / ISL Series Application   High quality construction to ensure a perfect seal between oil pump, gasket, and engine block Direct replacement for OE oil pump part number 3800828 Cummins 6C / ISC / ISL Series Application

    $82.17
  • Engine Kit, ISC Cummins

    PAI Truck Parts

    Engine Kit, ISC Cummins

    ENGINE KIT, ISC CUMMINS Engine KitCummins 6C Series Engine Application

    $1,150.00
  • Spacer  Plate

    PAI Truck Parts

    Spacer Plate

    SPACER PLATE OEM: 6I4421 Cylinder Block Spacer Plate.338in thicknessCaterpillar 3406E / C15 / C16 / C18 Series application

    $419.93
  • Injector Kit

    PAI Truck Parts

    Injector Kit

    Injector kitDetroit Diesel Series 60 application Replaces Part Number 23537123

    $7.34
  • CAT 3406E Camshaft

    PAI Truck Parts

    CAT 3406E Camshaft

    Camshaft | Caterpillar 3406E / C15 / C16 / C18 Engines application

    $832.68
  • O-RING, O.E.# 109080

    PAI Truck Parts

    O-RING, O.E.# 109080

    O-Ring0.139 in C/S x 0.984 in ID3.53 mm C/S x 24.99 mm IDEPDM 75, Peroxide Cured Series # -214   Durable EPDM construction Multiple Engine Applications Replaces Part Numbers: 109080 3682360 5F1678

    $0.54
  • O-RING, O.E.# 212161

    PAI Truck Parts

    O-RING, O.E.# 212161

    O-Ring0.139 in C/S x 1.171 in ID3.53 mm C/S x 29.74 mm IDEPDM 70, Peroxide Cured / Optional TFE Green Series # -217 Replaces Part Numbers: 211126 212161 Durable EPDM construction Direct replacement for OE part 212161 Multiple Engine Applications

    $0.49