T3 Exhaust Manifold for 24V Cummins 1998.5–2002 | 3-Piece Expansion Design | CARB Exempt
The Diesel Power Source® T3 exhaust manifold for 1998.5–2002 Dodge Ram 2500 and 3500 trucks with the 5.9L 24-valve Cummins engine is a direct bolt-on replacement that flows 23% more than the factory manifold while typically adding 10–18 HP on a 400 HP truck. This 3-piece expansion joint design is cast from nickel-laced ductile iron, CFD designed and flow-tested, and includes three pre-tapped ports for pyrometer and boost pressure fittings. It replaces OEM part numbers 5014170AC, 5014170AD, 5014170AA, 5014170AB, and 3937187.
This manifold is CARB exempt with an Executive Order (EO) number, making it legal for use in California.
Why the Stock 24V Manifold Fails
The factory 24V Cummins exhaust manifold is a single-piece casting that cracks and warps over time from repeated thermal cycling. The rigid design cannot flex with temperature changes, so cracks develop at stress points, exhaust leaks form, and gaskets fail. Cracked manifolds rob the turbo of exhaust energy, raise EGTs, and create an exhaust smell in the cab. The DPS 3-piece expansion joint design solves this by allowing each section to expand and contract independently, absorbing thermal stress instead of transferring it to the casting.
Dedicated 24V Round Port Casting
Nearly every competitor manifold on the market uses the same casting mold for both 12V and 24V applications. They cast using a 12V rectangular port design and then machine the ports to fit the 24V round port head. This creates smaller, restricted port openings and poor exhaust flow transitions.
The DPS 24V manifold uses a dedicated round port mold designed specifically for the 24V head. The port geometry is optimized from the head flange through the runners to the collector, delivering unobstructed flow that is not possible with machined-down 12V castings. This is more expensive to manufacture, but the result is measurably better flow and performance.
Why Runner Size Matters: Bigger Is Not Always Better
Some competitor manifolds advertise oversized runners or large tube designs. While this sounds appealing, runners that are too large actually slow exhaust gas velocity. The exhaust then has to re-accelerate as it bottlenecks through the turbo flange, causing a loss in both horsepower and turbo spool-up. DPS has tested competitor manifolds with oversized runners that decreased horsepower by 40 HP on a 400 HP truck.
The DPS manifold uses CFD-tested runner geometry that maintains exhaust velocity from the ports through the collector while flowing 23% more volume than stock. The runners are sized to work with the turbo, not fight it. Additionally, the DPS design balances flow across all six cylinders so that end-port EGTs are much closer to center-port EGTs, reducing the hot spots that cause manifold cracking.
Specifications
| Specification | Value |
|---|---|
| Design | 3-piece expansion joint |
| Material | Nickel-laced ductile iron |
| Flow Improvement | 23% more than stock |
| HP Gain | Typically 10–18 HP on a 400 HP truck |
| Turbo Flange | T3 (factory bolt-on) |
| Port Design | Dedicated round port mold (24V specific) |
| Coating | Black high-temperature ceramic (1,400°F rated) |
| Pyrometer Ports | 3 pre-tapped (pyro and boost pressure) |
| CARB Status | Exempt (EO numbered) |
| OEM Replacement | 5014170AC, 5014170AD, 5014170AA, 5014170AB, 3937187 |
| Fitment | 1998.5–2002 5.9L 24V Cummins (2nd gen) |
DPS 3-Piece Ductile Iron vs Stainless Steel Manifolds
| Feature | DPS 3-Piece Ductile Iron | Stainless Steel Manifolds |
|---|---|---|
| Thermal Expansion | Minimal — ductile iron expands less than stainless | Expands up to 2x more than ductile iron |
| Cracking | Expansion joints absorb thermal stress | Welds and rigid sections prone to cracking |
| Head/Gasket Stress | Low — expansion joints flex independently | High — extra movement stresses head, gaskets, bolts |
| Leak Risk | Low — less flange movement | Higher — gasket sealing issues from expansion |
| Longevity | Designed for long-term thermal cycling | Can fatigue faster under repeated cycles |
What's Included
- DPS 3-piece T3 exhaust manifold for 24V Cummins
- Black high-temperature ceramic coating
- Standard bolts and gaskets (upgradeable at checkout)
Optional upgrades (available at checkout):
- Serrated Spin-Lock Bolt Kit — upgraded bolts with teeth to prevent loosening
- Multi-Layer Gasket Kit with T3 Gasket — improved sealing over standard gaskets
Note: When selecting the Spin Lock Bolt or Multi-Layer Gasket Kit upgrade, the standard bolts and gaskets are not included. The upgraded components replace them.
Installation tip from customers: Consider ordering a stud kit for mounting the turbo, as the DPS manifold is thicker than the stock manifold. The included coolant line bracket may require minor adjustment for fitment.
Key Features
- 23% More Flow Than Stock — CFD designed and flow-tested
- 10–18 HP Gain — Typical on a 400 HP truck (competitors with oversized runners can lose 40 HP)
- 3-Piece Expansion Joint Design — Eliminates cracking from thermal cycling
- Dedicated 24V Round Port Mold — Not a machined 12V casting
- Balanced EGT Across Cylinders — End ports flow closer to center ports
- Nickel-Laced Ductile Iron — Handles heat without the expansion issues of stainless
- CARB Exempt (EO Numbered) — Legal for use in California
- Direct Factory Bolt-On — T3 flange matches factory manifold location
- 3 Pre-Tapped Ports — Pyrometer and boost pressure ready
- External Wastegate Compatible — Integrated wastegate provision
Black High-Temperature Coating
DPS exhaust manifolds are finished with a high-temperature black ceramic coating designed to handle extreme heat and real-world diesel performance conditions. This coating is rated for sustained temperatures up to 1,400°F, helping reduce surface heat, improve durability, and maintain a clean appearance under normal operating conditions. Because exhaust gas temperatures can vary significantly depending on tuning, load, and driving conditions, appearance changes may occur if those temperatures are exceeded.
Please note: The black ceramic coating is rated for temperatures up to 1,400°F. If exhaust gas temperatures exceed approximately 1,470°F, the coating may discolor and shift to a gray appearance. This is a normal result of excessive heat exposure and does not affect the performance or structural integrity of the manifold. Warranty does not cover coating discoloration or finish changes due to high EGT conditions.
OEM Cross-Reference
This DPS T3 exhaust manifold replaces the following OEM part numbers for the 5.9L 24-valve Cummins:
- 5014170AC
- 5014170AD
- 5014170AA
- 5014170AB
- 3937187
Fitment
This manifold fits 1998.5, 1999, 2000, 2001, and 2002 Dodge Ram 2500 and 3500 trucks with the 5.9L 24-valve Cummins engine. Direct factory bolt-on replacement with T3 turbo flange.
Have a 2003–2007 common rail truck? See the T3 Exhaust Manifold for 5.9 Cummins 2003–2007.
Have a 12V truck? See the T3 Exhaust Manifold for 12V Cummins 1989–1998.
Related 24V Cummins Products
Frequently Asked Questions
This DPS T3 manifold replaces Cummins/Dodge part numbers 5014170AC, 5014170AD, 5014170AA, 5014170AB, and 3937187 for the 1998.5–2002 5.9L 24-valve Cummins engine.
This is a dedicated 24V round port casting. Unlike most competitors who use a 12V rectangular port mold and machine it to fit 24V heads, DPS uses a separate mold engineered specifically for the 24V round port geometry. This delivers full-size, unobstructed port openings and better exhaust flow than machined-down castings.
Yes. All DPS 5.9 Cummins exhaust manifolds for the 24-valve engine have been granted an exemption by CARB and carry an Executive Order (EO) number. They are legal for installation and street use in California.
Stainless steel expands up to 2x more than ductile iron during heat cycles, which stresses the cylinder head, gaskets, and bolts, leading to leaks and failures. The DPS manifold is cast from nickel-laced ductile iron with 3-piece expansion joints that allow natural thermal flexing without transferring stress to the head or gaskets. It is designed for long-term durability under the repeated thermal cycling that diesel trucks experience.
Runners that are too large slow exhaust gas velocity. The exhaust then has to re-accelerate as it bottlenecks through the turbo flange, which costs both horsepower and turbo spool-up. DPS has tested competitor manifolds with oversized runners that decreased horsepower by 40 HP on a 400 HP truck. The DPS manifold maintains exhaust velocity through CFD-optimized runner sizing while flowing 23% more volume than stock.
Yes. Standard bolts and gaskets are included. You can upgrade to the Serrated Spin-Lock Bolt Kit and Multi-Layer Gasket Kit at checkout for improved sealing and bolt retention. Customers also recommend ordering a stud kit for turbo mounting, as the DPS manifold is thicker than stock.
21 Reviews
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Perfect for my 24v
Running this with an S300 setup and it fit exactly how it should. Flow is noticeably better than the restrictive stock manifold. No clearance issues either.
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Manifold
Quality piece. Lowered my EGTs from stock a few hundred degrees. Turbos louder and seems to spool a little faster. Easy install. Highly recommend.
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Great T3 option
Hard to find a good T3 manifold for these trucks. This one checked all the boxes and bolted up without a fight.
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Slight Adjustment
Overall really happy with it. Had to tweak one stud during install but nothing major. Once on, it’s been solid and no leaks.
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Exactly what I need
Straightforward install and great quality. Would buy again.
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DPS exhaust manifold
I would recommend getting a stud kit for mounting the turbo, as the new manifold is thicker than the stock one. The little bracket they send with for the coolant line is no where close to lining up with where it should be, but made it work. Overall everything was pretty straight forward.
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Excellent quality
This manifold is replacing a T4 manifold I had. I was looking for faster spool up than the T4 could give me at high altitude. This worked great. Fit and finish is great. Paint seems to stay on pretty well so far. This was for a 2nd gen setup in my 3rd gen.
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Nice Manifold
This is a nice manifold however it does not come with enough hardware and if you’re doing this in your garage, you’re gonna have a tough time. It should’ve had Stud bolts to hold the turbo on and the top two manifold bolts both to the head are impossible to put on they have to be modified.
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It’s great
It worked great. I was grateful it’s a lot better than stock and it’s better than any of those Amazon or eBay parts.
