What You're Actually Buying
This is an automatic slack adjuster, meaning it self-adjusts the brake clearance every time the brakes are applied, instead of you crawling under there with a wrench every service interval. R801073 is the Freightliner-side part number that shows up in Cascadia parts books.
Slack adjusters aren't universal even on the same truck model - the spline count on the camshaft end, the arm length, and the clevis pin spacing all have to match what's on the truck now. Get any of those wrong and the brake either won't stroke right or won't clear the drum.
Before you order, pull the old one off or at least get the number stamped on the arm. That's the fastest way to make sure R801073 is really what's bolted to your truck and not a running change Freightliner made mid-model-year.
Why All These Numbers Cross
BorgWarner made a lot of the actual castings that ended up under different labels - 065174, 065247, and K043197 aren't competing parts, they're the same manufacturing lineage sold through different channels. Alliance's N42AS series is Daimler's own parts program, and you'll see them list R801073 right alongside their own number because it's the same design, same spline, same torque rating.
The aftermarket numbers - AS1040, AS1140, AS1149, CS56040, and the rest - are other manufacturers building to the same spec so they bolt in the same location. They cross because the spline pattern, arm reach, and pushrod stroke length match up, not because everybody just copied a part number.
Where guys get burned is assuming all slack adjusters with '801073' or similar are interchangeable across different axle positions - front vs rear, or different cam sizes. Match yours by the number on the part, not by what axle you think it goes on.
Ordering From PartStop
We keep this one in stock in Tacoma for same-day pickup if you're local and need a truck back on the road today. Ships nationwide too if you're not near us - no reason a fleet in Ohio should wait longer than a fleet in Puyallup.
Comes with our 6+ month warranty. If it's wrong for your application or fails outside of wear-and-tear, we'll sort it out - just don't wait until the truck's back down another six months later.
Confirm fitment by VIN or by the number stamped on your old slack adjuster before you check out. A five-minute look now saves you a return shipment and a truck sitting on jack stands.
R801073 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to R801073. 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 |
|---|---|
| Alliance | N42AS AS1140, N42AS R801073, N42AS 065174 |
| BorgWarner | 065174, 065247, K043197 |
| Aftermarket | AS1040, AS1140, AS1149, CS56040, A32 3275H1152, PRO 801073, R803110, ASM801073, MK22102S, A2 3275U1139 |
Frequently asked questions
Does R801073 fit my 2019 Cascadia?
Probably, but Freightliner ran different slack adjuster specs across Cascadia model years and axle configurations. Check the number on your old unit or give us the VIN and we'll confirm before you order.
Is this the same as the BorgWarner 065174?
Same design lineage - BorgWarner built these and they've shown up under Freightliner's R801073 label as well as Alliance's N42AS number. They cross, but always verify against the number on the part you're pulling off, not just the truck model.
How do I know if I need a left-hand or right-hand slack adjuster?
Slack adjusters are position-specific based on which side of the axle they're on and rotation direction. Pull the old one and check the arm orientation, or send us a photo of the mounting position and we'll match it up.
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.