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)

Industrial/Off-Highway: Broad Cummins B-Series usage (4B/6B). Verify by ESN for non-automotive engines.

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.