What You're Actually Buying
This is a dual diaphragm air chamber - 30 square inch service side, 30 square inch spring side, hence the '30/30' everybody calls it. It's the piece bolted to your slack adjuster that does the actual pushing when you step on the brake pedal or when the parking brake cages/releases.
T3030DD covers a wide swath of Paccar applications - Kenworth and Peterbilt both - going back to 1990 model year trucks up through current production. That's a long run, and Paccar didn't keep the mounting pattern, push rod length, or stud spacing identical the whole time, so 'fits Paccar' doesn't mean grab one off the shelf blind.
Trailers use these too, obviously, since 30/30 chambers are about as universal as brake parts get in this industry. Doesn't matter if it's a dry van or a flatbed - if the axle's got air brakes, it's probably running something in this family.
Why These Numbers Cross
TKL30/30 and MGM's TR3030 and 3430051 all cross to the T3030DD because they're built to the same SAE/industry mounting bolt pattern and same 30/30 diaphragm sizing - that's how Bendix, Haldex, MGM, and TKL chambers end up interchangeable across brands in the first place. Same basic footprint, same air ports, same clamp ring style.
Where it gets you in trouble is push rod length and stroke - long stroke vs short stroke chambers look almost identical sitting on a shelf but they are not interchangeable, and running the wrong one messes with your slack adjuster geometry and stroke readings. Also check the yoke - some come with a clevis yoke installed, some don't, and swapping that piece isn't always included.
Bottom line: the bolt pattern crossing over doesn't guarantee the whole chamber is a straight swap for your specific application. Read the tag on the chamber you're pulling off - stroke length, part number, whatever's stamped there - before you order.
Ordering From PartStop
We keep T3030DD in stock in Tacoma and most orders that come in before early afternoon go out same day. If you're a local outfit needing to get a truck back on the road, will-call works too - call ahead and we'll have it up front.
Ship nationwide if you're not local - doesn't matter if you're in Spokane or Sheboygan, we'll get it moving. Comes with the standard 6+ month warranty like the rest of our brake chamber line.
Confirm fitment against your VIN or, better yet, the number stamped or tagged on the chamber you're replacing before you place the order. Air brake chambers are one of those parts where 'close enough' isn't - wrong stroke length can throw your push rod travel out of spec and that's a DOT issue, not just an inconvenience.
T3030DD Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to T3030DD. 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 |
|---|---|
| TKL | TKL30/30 |
| MGM Brakes | TR3030, 3430051 |
Frequently asked questions
Does T3030DD fit my 2015 Kenworth T680?
Probably, since Paccar ran this chamber across a lot of Kenworth and Peterbilt builds from 1990 up through current trucks - but 'probably' isn't good enough for a brake part. Pull the tag off your old chamber or check your VIN and match it up, or call us with the numbers and we'll confirm before you buy.
Is this the same thing as the MGM TR3030?
Same mounting pattern, same 30/30 diaphragm setup, and it'll bolt up the same way - that's why they cross. Different manufacturer, but functionally it's doing the identical job. Still worth checking stroke length matches what's coming off, long stroke vs short stroke isn't interchangeable even within the same size class.
How do I know if I need long stroke or short stroke?
Look at the chamber you're pulling - it'll usually be stamped or tagged with LS or SS along with the stroke measurement, or just measure the push rod travel yourself. If there's no tag left, check your truck's brake spec sheet or give us a call with the truck's VIN and we can usually track it down.
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.