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CUMMINS

CUMMINS 3958645 OEM CYLINDER HEAD GASKET (THICK) – RAM 5.9L (2003–2007)

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SKU:
CUM3958645
MPN:
3958645
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  • CUMMINS 3958645 OEM CYLINDER HEAD GASKET (THICK) – RAM 5.9L (2003–2007)
  • CUMMINS 3958645 OEM CYLINDER HEAD GASKET (THICK) – RAM 5.9L (2003–2007)
  • CUMMINS 3958645 OEM CYLINDER HEAD GASKET (THICK) – RAM 5.9L (2003–2007)
  • CUMMINS 3958645 OEM CYLINDER HEAD GASKET (THICK) – RAM 5.9L (2003–2007)
  • CUMMINS 3958645 OEM CYLINDER HEAD GASKET (THICK) – RAM 5.9L (2003–2007)
  • CUMMINS 3958645 OEM CYLINDER HEAD GASKET (THICK) – RAM 5.9L (2003–2007)
$316.95
724-785-4022

Description

Genuine Cummins

Cummins 3958645 — Cylinder Head Gasket (Thick, MLS) for 5.9L ISB

MPN: 3958645  |  Also Known As: head gasket (thick grade), MLS head gasket  |  Use Case: For engines with milled head and/or block deck

Why This Part

  • ✓ OE multi-layer steel gasket engineered for reliable sealing.
  • ✓ Thick grade compensates for resurfaced head/block during rebuilds.
  • ✓ Direct-fit for 2003–2007 5.9L ISB (24V common-rail) Ram.
  • ✓ Prevents compression/coolant leaks under towing or tune power levels.
OE Fit MLS Rebuild-Ready

Quick Specs

Type Multi-Layer Steel (MLS) cylinder head gasket, thick grade
OE Part # 3958645
Application For use when head and/or block have been resurfaced
Qty Required 1 per engine (sold individually)

Verified Fitment (Automotive)

Year RangeEngineChassis
2003–2007 Ram 5.9L ISB (24V Common-Rail) Ram 2500/3500

Industrial/Off-Highway: Common on QSB5.9 applications; verify by ESN before ordering.

Often Paired With

  • Head fasteners: ARP stud kit 247-4202 (popular upgrade) or OE bolts 3927063
  • Top-end gasket set (intake/exhaust manifold, valve cover, etc.)
  • Fresh coolant & thermostat housing seal (e.g., 3954829)
  • Machine shop check: head flatness & surface finish (RA) to OE spec

What’s In The Box

  • (1) Genuine Cummins Cylinder Head Gasket — Thick (3958645)
  • Fasteners and additional gaskets sold separately (see “Often Paired With”).

Install Tips

  • Measure piston protrusion and verify correct gasket grade for your build.
  • Follow torque sequence/specs precisely; chase threads and inspect dowels.
  • Retorque/inspect after initial heat cycles as required by your fastener choice.

FAQ

WILL THIS FIT MY 2003–2007 5.9L CUMMINS RAM?

Yes—this is the OE thick-grade head gasket for 2003–2007 5.9L ISB (24V common-rail) Ram 2500/3500. Always confirm by VIN/ESN.

WHEN SHOULD I USE THE “THICK” HEAD GASKET?

Use the thick grade when the cylinder head and/or block deck have been resurfaced during machine work, so compressed thickness restores proper piston-to-head and valve clearances.

CAN I REUSE MY OLD HEAD BOLTS?

We recommend new fasteners on any head-gasket job. Many builders upgrade to ARP 247-4202 studs for added clamping, especially with tuning or heavy towing.

IS THIS A GENUINE CUMMINS PART?

Yes—OE Cummins MLS head gasket, part number 3958645.

DOES THIS INCLUDE OTHER GASKETS?

No—this listing is the head gasket only. Add a top-end gasket set and any needed seals to complete the job.

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Additional Information

Vehicle Year:
2003,2004,2005,2006,2007
Vehicle Make:
DODGE
ENGINE:
5.9L
Part Type:
Stock Multi-Layer Head Gasket (Thick)
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