What The HT3B Does
The HT3B is the exhaust-driven charger sitting on the manifold of a 14L Cummins big-cam engine. Exhaust spins the turbine wheel, the shaft drives the compressor wheel, and the compressor stuffs pressurized air into the intake. Lose that and the engine still runs, it just runs down on power, smokes under load, and burns more fuel doing less work.
This aftermarket unit uses cast turbine and compressor housings machined to the factory mounting flanges, a high-nickel-alloy turbine wheel for sustained exhaust gas temperature, and a dynamically balanced rotating assembly that is bench tested before it ships. The intent is a bolt-on swap onto the existing manifold and oil feed with no fabrication.
Typical failure modes are shaft play from oil starvation or coked oil, a cracked turbine housing from thermal cycling, wheel damage from debris coming down the intake, and seal leakage that pushes oil into the charge air cooler. Any of those show up as low boost, oil at the cooler drain, or a whine that changes pitch with load.
Why These Numbers Cross
3523415, 3801598, 3801613, 3524208, 3521551, 3522861, 3522862, 3522866, and 3522865 all point at the same HT3B family fitted to the 855 big-cam platform. Over the production life of the engine, housings, wheel trims, and service kits got re-numbered as the charger was superseded, remanufactured, or released under a different service package. The core casting, flange pattern, and rotating group stayed common.
That is why a tag on the old unit may read one number while the parts book calls out another. Supersession chains on Cummins-era turbochargers are long, and a truck built in one year can carry a service charger from a later number. The numbers are listed here for identification only so you can match what is physically on your engine.
Because these variants can differ in compressor trim, wastegate presence, or discharge clock position, the cross list is a starting point and not a fitment promise. Confirm against the number stamped on the compressor housing tag of the unit you are pulling, or against your engine serial number, before you order.
Check Before You Order
Pull the tag off the old turbo first. If the tag is gone or painted over, measure the compressor inlet and discharge, note the V-band or flange style on the turbine outlet, and photograph the clock position of the housings relative to the manifold. Those three things settle most mix-ups faster than a parts book search does.
Then find the root cause. If the old charger failed from oil starvation, replace the feed and drain lines and confirm you have clean oil pressure at the head before the new unit goes on. If a wheel is chewed up, find the debris source. Bolting a new charger onto a dirty intake buys you a second failure.
3523415 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 3523415. Use them to identify the part — then confirm the exact fit by VIN or the number stamped on your old unit before you order. An interchange is a starting point, not a fitment guarantee.
| Brand / Line | Cross-Reference Numbers |
|---|---|
| Cummins/Holset | 3801598, 3801613, 3524208, 3521551, 3522861, 3522862, 3522866, 3522865 |
Frequently asked questions
How do I know if my turbo is the HT3B or a different Holset?
Read the data tag on the compressor housing. It carries the model and part number. If the tag is unreadable, compare the inlet and outlet sizes and the flange pattern to the unit you are ordering, and cross-check your engine serial number. A 3523415 and its supersessions are all HT3B family units for the 855 big-cam.
Will this bolt to my NTC400 without modification?
It is machined to the factory mounting flanges and is intended as a direct replacement on NTA855, NTC400, and NTC320 big-cam engines. That said, clock position and outlet style varied across the production run. Verify your engine serial number and the number on the old charger before ordering. Cross-reference identifies the part, it does not guarantee fit on your specific truck.
I have oil in my charge air cooler. Is the turbo bad?
Often yes, but not always. Excessive shaft end play or radial play at the compressor wheel points at worn bearings and failed seals. Check play by hand with the intake pipe off. If play is within spec, look at a restricted drain line, crankcase pressure, or a plugged breather pushing oil past the seal instead.
Not sure it fits? We check before you pay.
Run your VIN and we’ll match parts to your exact truck, or call the counter — a person who knows trucks verifies fitment by OEM number before the order ships. No wrong-box returns.
More cross-reference guides
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