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AC Plumbing Kit - Freightliner Cascadia - Suction and Discharge Lines
SKU: 31313003
+ 1 reviews
$410.00 -
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Caterpillar Front Engine Upfit - C15/3406E - 12/6 Groove Serpentine
SKU: 99102006-Base
$4,615.00 - $4,695.00 -
Caterpillar Front Engine Upfit - C15/3406E - 8/6 Groove Serpentine
SKU: 99102005-Base
+ 1 reviews
$3,695.00 - $3,755.00 -
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Detroit Front Engine Upfit - 10/8 Groove Serpentine Kit - Fits Kenworth T660/T800 or Peterbilt 386
SKU: 99302002-1
$1,815.00 -
Detroit Front Engine Upfit - 10/8 Groove Serpentine Kit - Fits Kenworth W900 or Peterbilt 388/389
SKU: 99302002
$1,815.00
The Final-Stage Parts That Finish a Conversion Right
Engine upfit is one of the most commonly overlooked parts of a conversion. Many customers assume that because they have a dressed donor engine, they can simply set it in the chassis and connect everything. That is rarely true.
Fan hubs, fan blades, accessory drives, intake manifolds, thermostat housings, oil pans, and power steering pumps are often engine and chassis specific. Using the wrong combination creates clearance problems, alignment issues, and custom fabrication that could have been avoided.
Key areas that typically need attention:
- Fan Hubs – These are engine, chassis, and model specific. The center height from the crankshaft to the fan hub must match the truck. A Peterbilt 389 requires approximately 15.75", while a Western Star 4900 needs around 20". The wrong hub leaves the fan blade off-center in the shroud.
- Fan Blades – Blade count, offset, bolt circle, and pilot diameter all matter. A Paccar engine uses a different pilot and bolt circle than a CAT C15, so the blades are not interchangeable. The wrong offset can cause contact with the engine or prevent the blade from engaging the shroud properly.
- Serpentine Belt Systems – The most common upgrade. Serpentine belts offer clear advantages over older V-belt setups, but they require matching brackets, idlers, and pulleys so everything stays in alignment. We still support V-belt configurations when needed.
- A/C System – Updating to current compressor and line fittings (at the compressor, expansion valve, and condenser) avoids the need for custom one-off lines later.
- Intake Manifold & Thermostat Housing – These vary by the original chassis the engine came from. A Detroit Series 60 that came out of a Freightliner has a different intake location and angle than one originally installed in a Peterbilt. Thermostat housings are also vertical or horizontal, which determines the correct upper radiator tube.
- Oil Pan Configuration – Front-sump vs rear-sump pans are dictated by the original truck. A front-sump pan can interfere with a set-forward front ax
- Power Steering Pump – Rotation is engine-specific. A Cummins power steering pump will not work on a CAT engine, and vice versa.
Shop Story: A customer installed a CAT C15 that came out of a Western Star into a Peterbilt 389 and reused the original fan hub. The center height was wrong, so the fan blade sat too high in the shroud.
To compensate, the shop installed a 30" fan blade instead of the recommended 32" blade. Within a few weeks the customer was complaining of high operating temps and the fan running constantly because there was not enough blade capacity to properly cool the engine. Once the correct fan hub was installed that allowed the proper 32" blade, the overheating issues went away immediately.
Matching Engine Upfit Parts to What Your Swap Actually Needs
Engine upfit parts aren’t a single checklist item. They break down by which systems the new engine disrupts. Knowing which categories apply to your build keeps you from ordering parts you don’t need - or missing the ones that will stop the truck from running correctly.
Key Fact: A/C compressor mismatches are one of the most common upfit oversights, since the compressor itself may bolt up to the bracket but the fitting that attaches to the compressor does not accept the style of fitting on the existing AC lines.
Confirming which of these categories applies before you order engine upfit parts is the difference between a one-pass install and multiple separate follow-up orders. Call our team at 888-564-8890 with your engine and chassis details, and we'll map out exactly which upfit parts your build needs.
Frequently Asked Questions
Are engine upfit parts specific to each engine, or mostly universal?
Specific. Fan hubs, blades, and serpentine kits are all sized to the engine and chassis pairing, so confirm your exact combination before ordering.
Do I need engine upfit parts if I'm keeping the original accessory drive?
If the engine and chassis are the original factory combination, you usually do not need upfit parts. These components become necessary when you are installing a different engine into the chassis, because the accessory drive, fan hub, A/C, and related systems rarely line up the same way.
What should I order alongside engine upfit parts for a complete build?
Most conversions also need mounting brackets, air intake piping, and matched fan hubs and blades to finish the front-end accessory system.
Discover the Right Engine Upfit Parts for Your Swap With Kustom Truck Parts
Need help identifying the right engine upfit parts for your swap? Call our team at 888-564-8890. We'll walk through your engine, chassis, and accessory setup before you order.
