Learning How to Decode a Holset Turbocharger Part Number is one of the most useful skills a diesel mechanic or fleet manager can pick up, because the numbers stamped on that housing tell you exactly what you’re working with before you ever pull the unit off the engine. Holset, now owned by Cummins Turbo Technologies, has produced millions of turbos across the HX, HE, HY, and WH series, and every one of them carries a coded identity. Get fluent in that code and you can source the right replacement in minutes instead of guessing.
At PT Turbo we’ve been reading these numbers since 1978. Over 45+ years in business we’ve handled tens of thousands of Holset units across on-highway trucks, ag equipment, and marine applications. This guide breaks down the numbering system the way we teach it on the shop floor.
Where to Find the Holset Part Number
Holset turbos carry a stamped or laser-etched nameplate, usually riveted or attached to the compressor housing or the center bearing housing. On many units the numbers are also die-stamped directly into the compressor cover.
You’ll typically see two critical numbers: the HOL number (the assembly or part number) and the CPL or serial number. Don’t confuse them. The assembly number identifies the exact turbo build. The serial number is a unique production identifier for that individual unit.
- Assembly number: usually 7 digits (older) or 10 digits (newer), e.g. 3599811 or 4043600.
- Serial number: alphanumeric, unique to the unit, used for warranty and traceability.
- Cummins CPL: found on the engine dataplate, cross-references the correct turbo build.
Always record both numbers before ordering. If the nameplate is missing or corroded, the casting numbers cast into the turbine and compressor housings become your fallback reference.
How to Decode a Holset Turbocharger Part Number: The Number Structure
Holset uses a sequential assembly numbering system rather than a fully descriptive code like some manufacturers. This trips people up, because unlike a Garrett or Mitsubishi number, a Holset assembly number does not spell out frame size and trim in the digits themselves.
Instead, the assembly number points to a specific documented build in the Cummins/Holset database. That build defines everything: compressor wheel, turbine wheel, housing A/R, actuator type, and calibration.
The three numbers you need to understand
1. The model designation. This is the family and frame, such as HX35W, HE351VE, HE300VG, or HX40. The letters and digits here DO carry meaning.
2. The Holset assembly (HOL) number. This 7 or 10 digit number identifies the complete turbo assembly, including its exact internal spec.
3. The revision or supersession suffix. Holset frequently supersedes older assembly numbers with updated builds. An older number may cross to a newer, improved unit.
Decoding the model designation letters
| Code | Meaning |
|---|---|
| HX | Standard wastegated or fixed-geometry frame |
| HE | Holset “H-series Electronic,” often variable geometry |
| HY | Variable geometry with hydraulic/electric actuation |
| WH | Wastegated H-series |
| Number (35, 40, 50, 55) | Approximate frame/turbine size |
| W | Wastegated variant |
| VE / VG | Variable geometry, electric or variable geometry actuation |
So an HX35W is a 35-frame fixed geometry turbo with a wastegate, the classic unit on the 5.9L Cummins. An HE351VE is a 35-frame variable geometry turbo with electronic actuation. The frame number gives you a ballpark on airflow capacity, while the suffix tells you the actuation strategy.
If you’re working on any of these specific frames, we’ve published detailed application guides worth bookmarking: the Holset HX35 fitment guide, the HE351VE specs and replacement guide, and the HE300VG variable geometry operation guide.
Worked Example: Reading a Real Holset Number
Let’s take a common HX35W assembly number, 3592766. Here is how a tech at our bench breaks it down.
- Model: HX35W, a 35-frame wastegated turbo.
- Assembly number 3592766: points to the exact build spec, in this case a common 1994-1998 Dodge Ram 5.9L 12-valve application.
- Serial number: a unique per-unit code, irrelevant to spec but needed for warranty.
Now compare that to a variable geometry unit like the HE351VE assembly number 4043600, used on 2007.5-2012 6.7L Cummins. Same frame family, completely different actuation and internal geometry. The variable geometry design uses sliding nozzle vanes controlled by an electronic actuator, so the correct assembly number is critical, because the calibration is matched to the engine ECM.
This is why you never order a VGT turbo by frame size alone. Two HE351VE units with different assembly numbers can have different vane geometry and ECM calibration, and the wrong one will throw fault codes or cause boost control problems.
Actuators: The Detail That Sinks Most Orders
The single most common mistake we see is ordering a turbo or a replacement actuator that doesn’t match the calibration of the original. On both variable geometry and wastegated turbos, the actuator is calibrated to a specific build. Swap in the wrong one and boost control goes out the window.
While Holset uses electric actuators on its VGT units, plenty of the Garrett and Mitsubishi turbos we service alongside them use pneumatic actuators, and matching the right actuator to the turbo build is the same discipline. Here are actuators we stock that illustrate the range of applications and price points.
| Actuator | SKU | Price |
|---|---|---|
| Garrett Pneumatic Actuator | 757979-5102 | $240.94 |
| Mitsubishi Pneumatic Actuator TD03 | 49S3118761 | $104.33 |
| Mitsubishi Pneumatic Actuator | 4918918935 | $83.99 |
| Garrett Pneumatic Actuator | 445963-0040 | $465.52 |
The Garrett unit is a common replacement for many mid-range diesel turbos, available from PT Turbo for $240.94 view the Garrett Pneumatic Actuator 757979-5102 here. For smaller TD03 frame applications, the Mitsubishi actuator runs $104.33 view the Mitsubishi TD03 Actuator 49S3118761 here.
If you’re chasing a budget-friendly Mitsubishi replacement, the 4918918935 actuator is $83.99 view the Mitsubishi Pneumatic Actuator 4918918935 here. And for higher-boost applications that demand a heavier duty unit, the Garrett 445963-0040 comes in at $465.52 view the Garrett Pneumatic Actuator 445963-0040 here.
The lesson carries straight back to Holset: always confirm the actuator part number and calibration against the original turbo assembly number, not just the frame.
Cross-Referencing and Supersessions
Holset regularly supersedes assembly numbers. An older 7-digit number often crosses to a newer 10-digit build with running changes to the wheel, seal package, or actuator. When you enter the original number in a Holset or Cummins parts system, it will flag the current supersession.
This matters for two reasons. First, the superseded unit is usually the improved version and is what you want. Second, if you order the obsolete number blindly from a reseller, you may get an outdated build with the very weakness that got it revised.
When the nameplate is gone, cross-reference by:
- Engine make, model, and displacement
- Cummins CPL number from the engine dataplate
- Casting numbers on the turbine and compressor housings
- Vehicle VIN for OEM applications
Not sure what you’re looking at? Send us photos of the nameplate and castings through our contact page and we’ll identify the exact build. We do this every day. Cummins Turbo Technologies operates under the BorgWarner and broader turbo industry standards, and cross-referencing correctly keeps you inside those specs.
New vs Remanufactured: Choosing the Right Replacement
Once you’ve decoded the number and confirmed the correct build, you have a sourcing decision. Here’s how new and remanufactured Holset units stack up.
| Factor | New OEM Holset | Remanufactured |
|---|---|---|
| Cost | Highest | Typically 30-50% less |
| Availability | Can have long lead times | Often in stock |
| Spec accuracy | Exact OEM build | Matched to OE
Cross-Reference & Superseded Part NumbersThe turbochargers covered in this article match or supersede the following OEM and manufacturer part numbers. If you are searching by part number, these are the units stocked by PT Turbo for this application: 3591890 • 3592773 • 3598273 • 3598483 • 4030045 • 4030227H • 4030269 • 4030273 • 4030715 • 4030720 • 4030736 • 4030747 • 4030757 • 4030763 • 4030767 • 4030780 • 4030782 • 4030784 • 4030786 • 4030793 • 4030831 • 4030835 • 4030845 • 4030847H • 4030858 • 4030861 • 4030870 • 4030877H • 4030892 • 4030894H • 4030914 • 4030915 • 4030916 • 4030918H • 4030923 • 4030926H • 4030930 • 4030935 • 4030945 • 4030963 • 4030967 • 4031254H • 4031315 • 4031327 • 4031381 • 4031435 • 4031461 • 4031488 • 4032006 • 4032029 • 4032046 • 4032219 • 4032238H • 4032259 • 4032262 • 4032265 • 4032277 • 4032284 • 4032292 • 4032294H • 4032304H • 4032305 • 4032306 • 4032664 • 4032706 • 4032721 • 4032739 • 4032769 • 4032869H • 4032975 • 4034013 • 4034055H • 4034144H • 4034145H • 4034150H • 4034256H • 4034294H • 4034320H • 4034322H • 4034356H • 4034384H • 4034387H • 4034464H • 4034499 • 4035465 • 4036553 • 4037504 • 4038545 • 4038889 • 4040391 • 4042573 • 4043168 • 4043564 • 4044633 • 4044721 • 4044722 • 4044830 • 4047073H • 5503312H • 6454763H Can’t find your number above? Contact PT Turbo — our team has been matching part numbers since 1978. Need This Turbo Rebuilt? Need a Turbocharger?PT Turbo has rebuilt and sold turbochargers since 1978. We stock remanufactured units for Cummins, Duramax, Power Stroke, Detroit Diesel, and more — backed by a 12-month unlimited mileage warranty and same-week shipping from San Bernardino, CA. 📞 (909) 824-1020 · 346 S I St. #3, San Bernardino, CA 92410 · [email protected] More From PT Turbo |
