Product Description
Cummins 3920781 — Genuine Rocker Arm Bolt (Rocker Lever) for 5.9L 6BT
MPN: 3920781 | Also Known As: rocker arm bolt, rocker lever bolt, hex flange cap screw | Cross-Refs (ID only): 3902344, 3903940, PAI 040050
Genuine Cummins hex-flange fastener used to secure the rocker lever assembly to the cylinder head on B-Series 5.9L applications. Built to OE metallurgy and thread accuracy for stable valve-train geometry and long service life. Sold individually.
Features & Benefits
- OE fit & finish—correct shank length, thread pitch, and flange profile for the rocker pedestal.
- High clamp load consistency for reliable valve timing and reduced fastener loosening.
- Hex-flange head distributes load without a separate washer.
- Direct replacement for worn, stretched, or damaged rocker bolts.
Verified Fitment (Automotive)
| Year Range | Engine | Chassis |
|---|---|---|
| 1989–1998 | 5.9L 12V (6BT) | Ram 2500/3500 |
Industrial/Off-Highway: Broad Cummins B-Series usage (4B/6B). Verify by ESN for non-automotive engines.
Compatibility Notes:
- This listing targets 1989–1998 5.9L 12-valve (6BT) Ram applications.
- For 1998.5–2002 5.9L 24-valve engines, Cummins uses a different rocker assembly bolt (commonly 3940195)—confirm by VIN/ESN before ordering.
Specifications
- Type: Rocker arm / rocker lever bolt (hex-flange cap screw)
- Thread/Size: M12 × 1.75
- Overall Length: ~180 mm
- OE Part Number: 3920781
- Cross-References (ID only): 3902344, 3903940, PAI 040050
- Quantity Required: Sold individually; order as needed per service procedure
Often Paired With
- Rocker levers: 3910810 (exhaust), 3910811 (intake)
- Rocker lever shaft: 3922488
- Head bolt (short): 3920779 (if servicing head fasteners)
What’s In The Box
- (1) Genuine Cummins Rocker Arm Bolt (3920781)
Installation Tips
- Clean threads and seating surfaces; inspect pedestals and shaft for wear.
- Follow the Cummins service manual for torque spec, sequence, and any threadlocker requirements.
- Re-check valve lash after any rocker service.
FAQ
WILL THIS FIT MY 1989–1998 5.9L CUMMINS RAM?
Yes—3920781 is the OE rocker arm/rocker lever bolt for 1989–1998 5.9L 12-valve (6BT) Ram 2500/3500. Confirm by VIN/ESN if your truck has mid-year changes.
IS THIS THE RIGHT BOLT FOR 24-VALVE (1998.5–2002)?
No. Most 24-valve applications use a different rocker assembly bolt (commonly 3940195). Verify by VIN/ESN.
WHAT SIZE/THREAD IS THIS BOLT?
M12 × 1.75, approximately 180 mm overall length, hex-flange head design.
HOW MANY DO I NEED?
Sold individually. Order the quantity required for the rocker assemblies you’re servicing per the factory procedure.
DO I NEED WASHERS OR SPECIAL HARDWARE?
No separate washer is typically used—the integral flange provides the bearing surface. Reuse any OE spacers if your build requires them.
IS THIS A GENUINE CUMMINS PART?
Yes—OE Cummins part 3920781.
