Short answer: a West Coast exhaust stack is sized by two numbers, not by truck model. Measure the outside diameter of the pipe the stack slides onto and the length from the clamp joint to the top lip. Everything else — mitre or straight cut, wall thickness, polished or raw finish — is a preference layered on top of those two measurements.
A 4–8 in diameter range and an 18–84 in length range cover an enormous number of trucks, which is why the same listing can serve a class 7–8 tractor and a heavy pickup. It is also why ordering the wrong size is the most common failure on this part: the range describes what can be built, not what your truck needs.
What is a West Coast exhaust stack?
A West Coast stack is a vertical exhaust pipe that rises behind or beside the cab and exits above the roofline, rather than under the truck. The name comes from the style — a tall, polished, often mitre-cut pipe — not from a brand or a fitment standard.
On this part the section is straight, TIG welded, and finished in polished stainless steel. It replaces a rusted, cracked or failed factory stack and reuses the truck's existing clamp and bracket hardware. It is not vehicle-specific.
Related: How to Measure Exhaust Pipe Diameter Correctly and Mandrel Bend vs Press Bend. Parts covered here: Stainless Steel 90° Elbow.
If you are shopping for the horizontal, under-body parts instead, those live under exhaust systems and fabrication parts — a stack is a different component with a different measuring method.
What size West Coast exhaust stack do I need?
Two measurements decide it. Take both before you order, because neither can be guessed from the truck's model year or engine.
- Diameter — the outside diameter of the pipe the stack slides onto. Not the diameter of the old stack's outer shell, and not the inside diameter of the new one.
- Length — from the clamp joint to the top lip, not from the cab roof and not the old stack's total length including the section that sat inside the clamp.
The order form on this listing covers 4–8 in diameter and 18–84 in length, so one of those combinations is built for you. The listing does not ship a universal part that fits itself to the truck.
How do you measure exhaust stack diameter?
Measure the pipe you are joining, across its outside, with a caliper or a diameter tape. The stack slides over that pipe and is compressed by a clamp, so the stack's nominal size has to match the pipe's outer diameter.
The failure case is worth stating plainly: a 5 in stack will not clamp onto 4 in tube. A clamp closes a small gap between two matching diameters; it cannot close a full inch. If you measure 4 in and order 5 in, the part arrives oversized and no amount of tightening will seal it.
Two things trip people up here:
- Pipe versus shell. The old stack's outer shell may be larger than the pipe it slipped over. Measure the joint, not the visible body.
- Nominal versus actual. Exhaust tube sold as 5 in is not always exactly 5.000 in at the outside. Measure the actual pipe with a caliper rather than trusting the label on a previous purchase.
How is stack length measured?
From the clamp joint to the top lip. That is the visible, load-bearing length of the pipe — the part that stands above the joint and carries the outlet where you want it.
Measuring the old stack end to end will overstate the replacement, because the removed section includes the slip joint that sat inside the clamp. If the old pipe was cut down at some point, or the clamp sits lower than factory, the difference can be several inches.
Height is a separate decision from length:
- Measure the clearance from the top lip to whatever the truck passes under — a canopy, a workshop door, a low bridge on your regular route.
- Confirm the top lip clears the cab roof by the margin you want. A stack that ends level with the roof pushes exhaust close to the cab intake area.
- Check your local height and exhaust-position rules before committing to a dimension. Requirements vary by jurisdiction, and this part is supplied to your measurement, not to a regulation.
Mitre cut or straight cut?
Both are single-section pipes; the difference is how the top is cut.
| Top cut | What it looks like | What it changes |
|---|---|---|
| Mitre cut | Angled opening, the classic West Coast profile | The outlet faces away from vertical, so the opening is less exposed to direct rainfall. It does not replace a rain cap. |
| Straight cut | Flat horizontal opening | Straight-up exit with a clean edge. More exposed to rain and debris, so a cap matters more. |
The listing is built with a mitre-cut top. If you need a straight cut, say so when you confirm the order rather than assuming it will be adjusted.
What wall thickness should you choose?
The build range is 1.5 mm to 2.5 mm. Thicker is not automatically better — it trades weight and heat behaviour against resistance to damage.
| Wall | Behaviour | Suits |
|---|---|---|
| 1.5 mm | Lightest of the range. Heats through faster and dents more easily at the clamp joint. | Builds where weight and cost matter more than abuse resistance. |
| 2.0 mm | Middle ground: reasonable stiffness without much added mass. | General replacement on a truck that is not worked hard. |
| 2.5 mm | Most resistant to distortion and denting at the joint. Heaviest of the range. | High-vibration, high-mileage or frequently loaded trucks. |
Wall thickness does not change the outside diameter you order. It changes how much the pipe resists deformation once a clamp is torqued onto it — which is exactly where a thin stack on a vibrating truck tends to fail first.
Polished or raw finish?
Polished stainless is the listed finish and the one that gives the West Coast look. A raw, unpolished finish is available on request.
Raw is usually chosen when the stack will be painted, coated or wrapped, because a polished surface has to be keyed before paint will hold. Polished is chosen when the metal is meant to be seen and cleaned rather than coated.
Stainless grades differ in corrosion and heat behaviour, and the grade is not the same across every stack on the market. If you are comparing suppliers on material rather than finish, the 304 vs 409 stainless comparison covers what actually differs.
What is in the box — and what is not
The stack is supplied on its own, as a single section. It does not include:
- Clamps
- Brackets or hangers
- Rain cap
On most trucks the existing clamp and bracket hardware is reused, which is why the part is priced as a single section rather than a kit. If the clamp is seized, cracked or the wrong size, source it separately — see hardware and clamps. If the joint needs to be extended or adapted, straight tubing is the relevant stock.
Plan the clamp before the stack arrives. A correctly sized stack with a failed clamp is still an undrivable truck.
How long does a made-to-order stack take?
This is a built-to-order part, not a shelf item. Length and diameter are produced to your specification, so dispatch takes roughly 25–30 days, plus transit to your address.
That timeline has two consequences worth planning around:
- Do not order against a deadline you have not checked. If the truck has to be back in service on a specific date, confirm the date before ordering rather than after.
- Confirm the build before production. Reply to your order confirmation with the four values — length, diameter, top style, finish — so the specification is confirmed in writing before the pipe is cut.
Fitment checklist before you order
- Outside diameter of the pipe the stack slides onto, measured with a caliper.
- Length from the clamp joint to the top lip you want.
- Clearance from that top lip to the lowest thing the truck passes under on its regular route.
- Top cut: mitre or straight.
- Finish: polished stainless, or raw on request.
- Wall thickness: 1.5, 2.0 or 2.5 mm.
- Condition and size of the existing clamp.
- Whether you need a rain cap, and whether you are reusing the existing brackets.
If you can supply the two numbers in items 1 and 2, the rest is a preference. If you cannot supply them, no supplier can confirm fitment for you — including this one.
Five mistakes that turn a stack order into a return
- Measuring the old stack's overall length. The slip joint that sat inside the clamp is not part of the new length.
- Using inside diameter. The stack is sized to the outside of the pipe it slides over.
- Reading "4–8 in" as one universal size. It is a build range, and the truck needs one specific number inside it.
- Assuming clamps and brackets are included. They are not, and a seized clamp discovered on install day adds days.
- Ordering inside the lead time. 25–30 days to dispatch is a production window, not a shipping estimate.
Specifications
| Type | West Coast exhaust stack, vertical, single section |
|---|---|
| Material | Stainless steel |
| Wall thickness | 1.5 mm – 2.5 mm |
| Length range | 18 in – 84 in (457 – 2,134 mm) |
| Diameter range | 4 in – 8 in (102 – 203 mm) |
| Inlet range | 4 in – 8 in |
| Surface | Polished |
| Welding | High-temperature TIG |
| Top | Mitre cut |
| Warranty | 1 year |
| Single gross weight | 15.0 kg |
| Single package size | 160 × 30 × 30 cm |
| Included | Stack only — no clamps, brackets or rain cap |
| Lead time | 25–30 days to dispatch, built to order |
Frequently asked questions
What size West Coast exhaust stack do I need?
You need two numbers: the outside diameter of the pipe the stack joins, and the length from that joint to the top lip you want. The listing covers 4–8 in diameter and 18–84 in length, so your two measurements select the build.
Will a 5 inch stack fit a 4 inch pipe?
No. A clamp closes a small gap between matching diameters; it cannot close one inch. Order the size that matches the outside diameter of the pipe you measured.
How do I measure stack length?
From the clamp joint to the top lip. Do not measure the old stack end to end, because that includes the slip joint that sat inside the clamp.
Are clamps or brackets included?
No. The stack is supplied as a single section. Clamps, brackets, hangers and rain caps are separate, and most trucks reuse their existing hardware.
Is the finish polished or raw?
The listing is polished stainless steel. A raw, unpolished finish is available on request, and is normally chosen when the stack will be painted or wrapped.
How long does delivery take?
Allow roughly 25–30 days for dispatch because the part is built to your size, plus transit time. Confirm any hard deadline before ordering.
Can I cut the stack down after it arrives?
The pipe is supplied to your specified length, so cutting should not be necessary. If you cut a finished stack you remove the finished top edge and have to re-cut and refinish it yourself — order the length you need instead.
Will it fit my truck?
It is a universal stack, so fitment depends on the diameter of the pipe it joins and the space above the cab. Without those two numbers, fitment cannot be confirmed by anyone — measure both before ordering.
Ordering the stack
If you have the diameter and the length, the rest is straightforward. The polished stainless West Coast exhaust stack is built from 4–8 in diameter and 18–84 in length, with a mitre-cut top, 1.5–2.5 mm wall and a one-year warranty. Reply to your order confirmation with length, diameter, top style and finish, and the build is confirmed before production starts.
If you are still deciding between a stack and an under-body system, start with exhaust systems. If you are building the joint around it, hardware and clamps and straight tubing cover the parts that are not in the box.