What This Seal Does
This is the seal that rides on the rear of the crankshaft where the shaft exits into the flywheel housing. It runs 6.00 in inner diameter and 6.757 in outer diameter, sized to the original 855 and N14 rear bore. Material is silicone, chosen because the lip sits in constant heat with crankcase pressure pushing behind it.
The dry-clutch designation matters. This seal is for engines running a dry clutch behind the flywheel, where any leakage lands directly on the friction disc. If your unit is a wet-clutch or torque converter setup, confirm the seal type on the old part before you order anything.
Failure shows up as oil pooling in the bottom of the bell housing, oil weeping from the flywheel housing inspection cover, or a clutch that grabs and chatters after a short soak. Techs often blame the clutch first. Pull the inspection plate and look at where the oil is actually coming from before condemning parts.
Why These Numbers Cross
3006737, 204829, and 211253 are Cummins-side references that all point at the same rear crankshaft seal envelope for the 855 and N14 family. Same bore diameter, same shaft diameter, same lip orientation. Numbers changed over the production life of the engine as the seal material and packaging were revised, but the dimensional interface stayed put.
136001 is the PAI aftermarket reference for the same seal. Aftermarket suppliers assign their own catalog numbers, so a shop pulling parts off an old invoice may have any one of these four written down for what is physically the same ring. All are listed here for identification only.
The practical check is dimensional. Measure the crank flange sealing surface and the housing bore on your engine. If they match 6.00 in and 6.757 in, and the engine is a dry-clutch 855 or N14, the numbers above are describing your seal. Cross-reference is a starting point, not a fitment guarantee.
Before You Order
Verify your engine serial number. The 855 family covers NT855, NTA855, NH855 and NTC variants, and N14 spans a long production run in Kenworth W900 and T800 and Volvo VNL chassis. Serial number is the fastest way to confirm which rear seal arrangement your engine left the factory with, especially on a rebuilt block with unknown history.
Inspect the crankshaft sealing surface while the flywheel is off. A grooved crank flange will chew a new seal in short order. If there is a visible wear track, plan for a wear sleeve or crank repair in the same job. Installing a fresh seal against a worn surface is why some rear main jobs leak again within weeks.
3006737 Cross-Reference & Interchange Numbers
These manufacturer and aftermarket numbers commonly cross-reference to 3006737. 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 |
|---|---|
| Cummins | 204829, 211253 |
| PAI | 136001 |
Frequently asked questions
Will 204829 or 211253 fit the same bore as 3006737?
Those Cummins numbers reference the same rear crankshaft seal interface on the 855 and N14 dry-clutch engines. They share the 6.00 in inner and 6.757 in outer dimensions. Confirm by measuring the bore in your flywheel housing and reading the number stamped on the seal you pull out. We do not guarantee fitment from a cross-reference alone.
How do I tell a rear main leak from a leaking rear cover gasket?
Clean the area, run the engine, then pull the flywheel housing inspection cover and look at the drip path. Oil coming from the center around the crank flange points at the rear main seal. Oil tracking down from a corner or a gasket line points elsewhere. On a dry clutch, a soaked friction disc almost always means the rear crank seal.
Is this seal the same for wet-clutch N14 applications?
This part is specified as a dry-clutch rear crankshaft oil seal. Wet-clutch and other rear arrangements can use different seal setups. Check the number on the seal you are removing and verify your engine serial number before ordering, since the 855 and N14 families ran multiple configurations over their production life.
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
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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.