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Peterbilt 357/378 Parts

Find the best Peterbilt 378 aftermarket parts in the business here at 4 State. The Peterbilt 378 semi truck represents all of the characteristics of the Peterbilt brand, and was a popular model with similar features to the Peterbilt 379. Pete truck models are a brand of choice for experienced truckers who need dependable semi trucks. 4 State Trucks has all the semi truck parts and accessories you need to make your Pete 378 stand out to showcase your unique personality. Whether you need aftermarket bumpers, exhaust, or fuel tanks, we've got you covered. Hit the open road in style and comfort with the best custom gear for your Peterbilt heavy duty truck or 18 wheeler.
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  • Price
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  • FREE SHIPPING OVER $249
    Air Brake Inversion Valve W/ Dust Shield On The Exhaust Port Replaces 14449, 280758

    Air Brake Inversion Valve W/ Dust Shield On The Exhaust Port Replaces 14449, 280758

    AFTERMARKET

    $58.99
    Air Brake Inversion Valve W/ 0.28 Inch Mounting Holes, Delivery, Supply & Control Ports* High Quality Air Brake Inversion Valve* Inlet Opening Descending Pressure Common Control: 45 PSI* Exhaust...
    09-05170505
    SKU:
    09-05170505
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $58.99
    Qty in Cart: 0
    Price:
    $58.99
    Subtotal:
  • FREE SHIPPING OVER $249
    Automatic Trailer Axles Haldex Type Slack Adjuster W/ 6 Inch Straight Arm Height Replaces 133.2841

    Automatic Trailer Axles Haldex Type Slack Adjuster W/ 6 Inch Straight Arm Height Replaces 133.2841

    AFTERMARKET

    $78.99
    Automatic Trailer Axles Haldex Type Slack Adjuster W/ 1.5 Inch - 28 Spline Diameter Replaces 133.2841* High Quality Slack Adjuster* Automatic, Trailer Axles, Haldex Type* 28 Spline Count* Straight...
    09-05170515
    SKU:
    09-05170515
    Product Type:
    Frame & Chassis
    Make:
    Universal Items
    $78.99
    Qty in Cart: 0
    Price:
    $78.99
    Subtotal:
  • FREE SHIPPING OVER $249
    MV3 Type Dash Valve W/ Integral Push-Lock-Connect Fittings Replaces 170.KN20619, 20560009

    MV3 Type Dash Valve W/ Integral Push-Lock-Connect Fittings Replaces 170.KN20619, 20560009

    AFTERMARKET

    $156.99
    MV3 Type Dash Valve 3.5 X 5.33 Inch C To C W/ 4 0.3 Inch Diameter Bolt Holes & 6 - 3/8 Inch PLC Ports* High Quality Dash Valve* MV3 Type Dash Control Module With Integral Push-Lock-Connect Fittings*...
    09-05170506
    SKU:
    09-05170506
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $156.99
    Qty in Cart: 0
    Price:
    $156.99
    Subtotal:
  • FREE SHIPPING OVER $249
    BPR1 Type Brake Proportioning Relay Valve W/ 5.5 PSI Crack Pressure & Mounting Bracket Replaces 170.065146

    BPR1 Type Brake Proportioning Relay Valve W/ 5.5 PSI Crack Pressure & Mounting Bracket Replaces 170.065146

    AFTERMARKET

    $61.99
    BPR1 Type Brake Proportioning Relay Valve W/ Control, Service, Supply & Deliver Ports* High Quality Relay Valve* BPR1 Type Brake Proportioning Relay Valve* 5.5 PSI Crack Pressure* Mounting Bracket...
    09-05170500
    SKU:
    09-05170500
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $61.99
    Qty in Cart: 0
    Price:
    $61.99
    Subtotal:
  • FREE SHIPPING OVER $249
    SR7 Type Spring Brake Modulating Valve Replaces 170.K021558

    SR7 Type Spring Brake Modulating Valve Replaces 170.K021558

    AFTERMARKET

    $162.99
    SR7 Type Spring Brake Modulating Valve W/ Control, Balance, Supply & Delivery Ports* High Quality Spring Brake Valve* SR7 Type Spring Brake Modulating Valve* Ports:  - (1) 1/4 Inch NPT Control Port ...
    09-05170501
    SKU:
    09-05170501
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $162.99
    Qty in Cart: 0
    Price:
    $162.99
    Subtotal:
  • FREE SHIPPING OVER $249
    Automatic Bendix Slack Adjuster W/ 28 Spline & Straight Arm Replaces 137.2810

    Automatic Bendix Slack Adjuster W/ 28 Spline & Straight Arm Replaces 137.2810

    AFTERMARKET

    $78.99
    Automatic Bendix Slack Adjuster 5/8 Inch - 28 Cleves Thread, 1 Inch A/F & 1 Inch C To C Pin* High Quality Slack Adjuster* Automatic Bendix Type* 28 Spline Count* Straight Arm* Clevis Kit Bendix Type...
    09-05170511
    SKU:
    09-05170511
    Product Type:
    Frame & Chassis
    Make:
    Universal Items
    $78.99
    Qty in Cart: 0
    Price:
    $78.99
    Subtotal:
  • FREE SHIPPING OVER $249
    MV3 Type Dash Valve Control Module W/ Integral Push-Lock-Connect Fittings Replaces 5009234, 801360

    MV3 Type Dash Valve Control Module W/ Integral Push-Lock-Connect Fittings Replaces 5009234, 801360

    AFTERMARKET

    $152.99
    MV3 Type Dash Valve 4.21 X 3 Inch C To C W/ 4 - .0275 Inch Diameter Bolt Holes* High Quality Dash Valve* MV3 Type Dash Control Module With Integral Push-Lock-Connect Fittings* Auxiliary Port Not...
    09-05170502
    SKU:
    09-05170502
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $152.99
    Qty in Cart: 0
    Price:
    $152.99
    Subtotal:
  • FREE SHIPPING OVER $249
    R12V Type Relay Valve W/ 4 PSI Crack Pressure & Mounting Brackets Replaces 170.065303

    R12V Type Relay Valve W/ 4 PSI Crack Pressure & Mounting Brackets Replaces 170.065303

    AFTERMARKET

    $54.99
    R12V Type Relay Valve 2.61 X 1 Inch C To C Bolt Holes W/ Service, Supply & Delivery Ports* High Quality Relay Valve* R12V Type Relay Valve* 4 PSI Crack Pressure* Mounting Bracket Included* Ports:  -...
    09-05170496
    SKU:
    09-05170496
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $54.99
    Qty in Cart: 0
    Price:
    $54.99
    Subtotal:
  • FREE SHIPPING OVER $249
    R12V Type Relay Valve W/ 4 PSI Crack Pressure & Mounting Bracket Replaces 170.065104

    R12V Type Relay Valve W/ 4 PSI Crack Pressure & Mounting Bracket Replaces 170.065104

    AFTERMARKET

    $52.99
    R12V Type Relay Valve 2.61 Inch C To C Bolt Hole Width W/ Service, Supply & Delivery Ports* High Quality Relay Valve* R12V Type Relay Valve* 4 PSI Crack Pressure* Mounting Bracket Included* Ports:  -...
    09-05170497
    SKU:
    09-05170497
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $52.99
    Qty in Cart: 0
    Price:
    $52.99
    Subtotal:
  • FREE SHIPPING OVER $249
    SR7 Spring Brake Valve W/ 2 - 1.38 Inch M1 Mounting Studs Replaces 170.K021560, K021560

    SR7 Spring Brake Valve W/ 2 - 1.38 Inch M1 Mounting Studs Replaces 170.K021560, K021560

    AFTERMARKET

    $172.99
    SR7 Spring Brake Valve W/ 3/8 PLC Control & Balance Port, 1/2 NPT Supply Port* High Quality Spring Brake Valve* SR7 Type Spring Brake Modulating Valve* Includes:  - 3/8 Inch PLC Control Port  - 3/8...
    09-05170507
    SKU:
    09-05170507
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $172.99
    Qty in Cart: 0
    Price:
    $172.99
    Subtotal:
  • FREE SHIPPING OVER $249
    Haldex Type Air Regulator Valve 3.5 Inch Height Replaces 170.KN31070

    Haldex Type Air Regulator Valve 3.5 Inch Height Replaces 170.KN31070

    AFTERMARKET

    $80.99
    Haldex Type Air Regulator Valve W/ 3/8 NPT Inlet & Outlet Port, 3/8 Inch 24 Threaded Post* High Quality Air Regulator Valve* Haldex Type* Adjustable From 10 PSI To 125 PSI* Includes:  - (1) 3/8 Inch...
    09-05170498
    SKU:
    09-05170498
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $80.99
    Qty in Cart: 0
    Price:
    $80.99
    Subtotal:
  • FREE SHIPPING OVER $249
    E3 Type Single Circuit Foot Valve W/ 4 - 1/2 Inch NPT Delivery Ports

    E3 Type Single Circuit Foot Valve W/ 4 - 1/2 Inch NPT Delivery Ports

    AFTERMARKET

    $56.99
    E3 Type Single Circuit Foot Valve W/ 1/2 Inch NPT Supply Port & 1/4 Inch NPT Auxiliary Supply Port* High Quality Foot Valve* E3 Type Single Circuit Foot Valve* Ports:  - (4) 1/2 Inch NPT Delivery...
    09-05170503
    SKU:
    09-05170503
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $56.99
    Qty in Cart: 0
    Price:
    $56.99
    Subtotal:
  • FREE SHIPPING OVER $249
    RT4 Type Multifunction Relay Valve W/ 4 PSI Crack Pressure Replaces 170.KN26000

    RT4 Type Multifunction Relay Valve W/ 4 PSI Crack Pressure Replaces 170.KN26000

    AFTERMARKET

    $76.99
    RT4 Type Multifunction Relay Valve W/ Service Tank, Control, Supply, Reservoir & Deliver Ports* High Quality Relay Valve* RT4 Type Multifunction Valve* 55 PSI PPV Closing Pressure* 4 PSI Crack...
    09-05170492
    SKU:
    09-05170492
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $76.99
    Qty in Cart: 0
    Price:
    $76.99
    Subtotal:
  • FREE SHIPPING OVER $249
    MV3 Type Dash Valve Control Module W/ Integral Push-Lock-Connect Fittings Replaces 170.800840WF, 2506-188-C

    MV3 Type Dash Valve Control Module W/ Integral Push-Lock-Connect Fittings Replaces 170.800840WF, 2506-188-C

    AFTERMARKET

    $190.99
    MV3 Type Dash Valve 4.225 X 3 Inch C To C W/ 4 M6 X 1 - 6H Mounting Holes* High Quality Dash Valve* MV3 Type Dash Control Module With Integral Push-Lock-Connect Fittings* Operating Temp From -40 To...
    09-05170493
    SKU:
    09-05170493
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $190.99
    Qty in Cart: 0
    Price:
    $190.99
    Subtotal:
  • FREE SHIPPING OVER $249
    MV3 Type Dash Valve Control Module W/ Knobs, 2 Spool Manifold & 6 - 1/4 Inch NPT Ports Replaces 101890, 14539

    MV3 Type Dash Valve Control Module W/ Knobs, 2 Spool Manifold & 6 - 1/4 Inch NPT Ports Replaces 101890, 14539

    AFTERMARKET

    $125.99
    MV3 Type Dash Valve 4.187 X 3.031 Inch C To C W/ 4 - 1/4 Inch 20 Threaded Mounting Holes* High Quality Dash Valve* MV3 Type Dash Control Module With Knobs* Manifold 2 Spool* (6) 1/4 Inch NPT Ports*...
    09-05170494
    SKU:
    09-05170494
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $125.99
    Qty in Cart: 0
    Price:
    $125.99
    Subtotal:
  • FREE SHIPPING OVER $249
    QR1C Type Quick Release Valve W/ 5-8 PSI Crack Pressure Replaces 170800348, 800348

    QR1C Type Quick Release Valve W/ 5-8 PSI Crack Pressure Replaces 170800348, 800348

    AFTERMARKET

    $17.99
    QR1C Type Quick Release Valve W/ NPT Supply, Delivery & Balance Ports* High Quality Quick Release Valve* QR1C Type Quick Release Valve* Integral Double Check Valve* 5 - 8 PSI Crack Pressure* Ports: ...
    09-05170488
    SKU:
    09-05170488
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $17.99
    Qty in Cart: 0
    Price:
    $17.99
    Subtotal:
  • FREE SHIPPING OVER $249
    PPDC Type Dash Valve W/ Integral Push-Lock-Connect Fittings Replaces 065661, 065661BXW

    PPDC Type Dash Valve W/ Integral Push-Lock-Connect Fittings Replaces 065661, 065661BXW

    AFTERMARKET

    $132.99
    PPDC Type Dash Valve 3 -1/4 Inch 20 Threaded Mounting Holes, 3 X 2.54 Inch C To C* High Quality Dash Valve* PPDC Type Dash Valve With Integral Push-Lock-Connect Fittings* Ports:  - (2) 3/8 Inch PLC...
    09-05170489
    SKU:
    09-05170489
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $132.99
    Qty in Cart: 0
    Price:
    $132.99
    Subtotal:
  • FREE SHIPPING OVER $249
    SR7 Type Spring Brake Valve Replaces 170.K021557

    SR7 Type Spring Brake Valve Replaces 170.K021557

    AFTERMARKET

    $155.99
    SR7 Type Spring Brake Valve W/ Control, Balance, Supply & Delivery Ports* High Quality Spring Brake Valve* SR7 Type Spring Brake Modulating Valve* Ports:  - (2) 1/4 Inch NPT Control Ports  - (1) 1/4...
    09-05170499
    SKU:
    09-05170499
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $155.99
    Qty in Cart: 0
    Price:
    $155.99
    Subtotal:
  • FREE SHIPPING OVER $249
    Spring Brake Control Valve W/ 3/8 Inch NPT Control Support & 3/8 Inch NPT Supply Port Replaces 170.110170

    Spring Brake Control Valve W/ 3/8 Inch NPT Control Support & 3/8 Inch NPT Supply Port Replaces 170.110170

    AFTERMARKET

    $86.99
    Spring Brake Control Valve W/ 2 - 1/2 Inch NPT Reservoir Ports & 4 3/8 Inch NPT Delivery Ports* High Quality Spring Brake Valve* Protected Reservoir Spring Brake Control Valve* Control And Supply...
    09-05170490
    SKU:
    09-05170490
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $86.99
    Qty in Cart: 0
    Price:
    $86.99
    Subtotal:
  • FREE SHIPPING OVER $249
    TP3 Type Tractor Protection Valve Rear Mounted Replaces 170.279000

    TP3 Type Tractor Protection Valve Rear Mounted Replaces 170.279000

    AFTERMARKET

    $26.99
    TP3 Type Tractor Protection Valve W/ .35 Inch Mounting Hole* High Quality Tractor Protection Valve* TP3 Type Tractor Protection Valve* Trailer Ports Are Both 1/2 in. NPT* Protects Tractor Air Supply...
    09-05170484
    SKU:
    09-05170484
    Product Type:
    Air, Electrical, & Safety
    Make:
    Universal Items
    $26.99
    Qty in Cart: 0
    Price:
    $26.99
    Subtotal:
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Adding your products to cart

The Peterbilt 357 and 378 are known for their no-nonsense durability and old-school style. Whether you’re hauling heavy loads or running construction jobs, these workhorses are built to last—and we’re here to help you keep them in top shape.

Why Choose Aftermarket Peterbilt 357/378 Truck Parts?

- Engineered for your model: Every part is made to fit and function with your 357 or 378—so you can skip the guesswork and get back to work. - Performance you can count on: Keep your truck running strong with engine, transmission, suspension, fiberglass Pete 357/378 hood shells, LED headlights, and cab lighting accessories designed to turn heads. - Trusted brands, proven quality: We only carry parts from manufacturers we trust, so you know you're getting durable, road-tested gear. - Quick shipping, expert help: Get your parts fast and reach out to our team if you need help finding the right fit—we’ve got your back.

Shop the Perfect Aftermarket Accessories for Peterbilt 357/378 Trucks


Whether you're restoring a classic or keeping your work truck rolling, our Peterbilt 357 and 378 parts are built to match the strength and legacy of these iconic models. We stock a wide selection of aftermarket and replacement parts designed specifically for Peterbilt 357 and 378 models. From critical mechanical components to sleek interior cab accessory upgrades, we’ve got what you need to maintain, repair, or customize your rig. Explore our full selection and get the parts you need to keep your rig road-ready.

Frequently Asked Questions About Peterbilt 357/378 Parts

What years and models are compatible with Peterbilt 357/378 parts?

Most aftermarket parts for Peterbilt 357/378 trucks are designed to fit models from 1987 through 2007. However, there are important differences between early models (1987-1999) and later models (2000-2007), particularly in hood mounting points and grille configurations. Always verify the specific year range listed for each part, as some components like bumpers and fenders may have changed mounting hole patterns after the 2000 model year update.

Are aftermarket bumpers as durable as OEM Peterbilt bumpers?

Quality aftermarket bumpers are typically made from 16-gauge steel (same as OEM) and feature triple chrome plating or powder coating for corrosion resistance. The main differences you'll find are in the finishing details and fitment precision. While a well-made aftermarket bumper can last just as long as OEM, pay attention to the warranty offered - reputable manufacturers typically provide at least a 1-year warranty on chrome finish and 3-5 years on structural integrity.

What tools and modifications are needed to install replacement parts?

Most bolt-on parts like bumpers, grilles, and headlight assemblies require basic hand tools including socket sets (typically 1/2" to 3/4"), wrenches, and a drill with metal bits for any minor adjustments. Common installation challenges include slight drilling to align mounting holes (especially on pre-2000 models) and adjusting bumper brackets for proper fitment. Professional installation typically takes 2-4 hours for major components like bumpers or hoods.

What's the difference between chrome, stainless steel, and painted finishes?

Chrome-plated steel offers the brightest mirror finish but requires regular polishing and can pit in harsh climates. Stainless steel (usually 304 grade) provides excellent corrosion resistance with less maintenance but has a slightly duller appearance. Painted finishes are the most economical and can be color-matched to your truck, but may need repainting every 5-7 years depending on exposure. For winter driOEMg or coastal areas, stainless steel typically offers the best long-term value.

How do I ensure proper fitment when ordering hoods, fenders, or bumpers?

Start by confirming your exact model year and checking whether you have a standard or extended hood configuration. Measure key mounting points on your current parts before ordering - bumper width should be either 18" or 20" depending on your model. For hoods and fenders, verify whether you have the single-headlight or dual-headlight configuration. When in doubt, provide your OEM number when ordering to ensure compatibility, as some mid-year production changes aren't reflected in standard model year listings.


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