What You're Actually Buying
This is the flex joint that sits in the exhaust piping between the turbo outlet and the aftertreatment box, letting the system absorb engine movement and thermal expansion without cracking the pipe or stressing the DPF can. On a DD15 Cascadia it takes a beating - heat cycling, vibration, road salt if you're running anywhere near Tacoma winters - and the braid eventually fatigues or the pipe rusts through at the weld.
21959395 crosses straight to Freightliner PN 21428536, which is the same physical piece Freightliner sold you at the dealer. Same stainless construction, same flex braid, same mounting flanges. We stock it because it's a common failure point and guys don't want to wait three days on a dealer order when the truck's sitting.
It also shows up on some Volvo VNL trucks from the 2009-2010 model years - not unusual, since Volvo and Freightliner shared some aftertreatment plumbing architecture around that era before emissions setups diverged further.
Cross Numbers - What Actually Matters
The Dorman numbers (674-6028, 674-6025) and the PN-3-B-022 reference in our system all point back to the same physical flex pipe geometry - flange bolt pattern, pipe diameter, and overall length matching what 21428536 replaced. Where guys get burned on flex pipe swaps isn't the flex section itself, it's flange orientation and overall stack-up length - if your truck's aftertreatment box sits at a slightly different height or angle from a running change, a pipe that's technically the right diameter can still bind up.
Don't go by year or model alone. Aftertreatment routing got revised more than once on both Freightliner and Volvo platforms during this era, and a part that fits a 2009 VNL might not fit a 2010 built later in the year. Pull the number off your old flex pipe or the flange it bolts to, or better yet, run your VIN to see what your truck actually left the factory with.
If your old pipe crushed or you can't read the stamped number anymore, measure flange-to-flange length and bolt pattern before you order. Saves a return shipment both ways.
Ordering From PartStop
We're in Tacoma and keep this one on the shelf because DD15 exhaust flex failures aren't rare - if you're local, call ahead and it's usually ready same day. Otherwise it ships nationwide, and stainless flex pipe travels fine in a box.
Comes with our standard 6+ month warranty. It's a direct replacement for the physical part, not a promise it'll bolt onto every truck that ever wore a Cascadia badge - confirm fitment against your VIN or the old part number before it goes in the cart, especially if you're cross-shopping between the Freightliner and Volvo applications.
Questions on flange orientation or length before you order - counter's got the spec sheet, just ask.
21428536 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 21428536. 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 |
|---|---|
| Cross-Reference | PN-3-B-022 |
| Dorman | 674-6028, 674-6025 |
Frequently asked questions
Does 21428536 fit my 2010 Volvo VNL?
Some 2010 VNLs used this flex pipe, some didn't depending on when in the model year it was built and what aftertreatment config it left the factory with. Check your VIN or match the number off your old pipe before ordering - don't just go by model year.
Is this the same as the Dorman 674-6028?
They cross-reference to the same flex pipe application - same flange pattern and length spec. Dorman makes it under their own part number, we stock the 21959395 version. Function's the same, just confirm against your old part's number since running changes happened on both platforms.
My old flex pipe is rusted through and I can't read the number - how do I know what to order?
Measure flange-to-flange length and check the bolt pattern on the flanges, or pull your VIN and we can look up what your truck left the factory with. Rust-through is exactly why we keep this one stocked - it's a common failure, not a rare one.
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
Need the part, not just the reading?
Every part below is a Premium Quality aftermarket Direct Replacement with published OEM cross-reference numbers, a 6+ month warranty and same-business-day shipping from Tacoma, WA. Not sure it fits? Run your VIN — or call and a person who knows trucks will verify fitment before you pay.