Product Description
The CUMMINS 3970305 OEM TIMING GEAR HOUSING is the genuine front gear case for 2003–2007 Ram 2500/3500 trucks equipped with the 5.9L ISB common-rail engine. This housing restores precise cam, crank, and idler gear alignment, seals the front of the block, and keeps your 5.9L running like it did off the showroom floor with true Cummins engineering and casting quality.
Verified Fitment – Automotive
- 2003–2007 Ram 2500, 5.9L ISB (24V common-rail)
- 2003–2007 Ram 3500, 5.9L ISB (24V common-rail)
- 1 housing required per engine (front timing gear housing / gear case)
Industrial / Off-Highway Usage
The 3970305 gear housing is also used on select Tier 3 5.9L ISB/QSB applications in industrial, marine, and off-highway equipment. Always verify fitment by engine serial number (ESN) for non-automotive engines before ordering.
Cross-Reference & Supersession
- Primary OE part number: Cummins 3970305
- Supersedes earlier gear housing part numbers: 3970303, 3970304
- Related/alternate casting often seen in the field: 3970306 (verify by ESN/build)
- For 6.7L applications, see CUMMINS 4934041 OEM TIMING GEAR CASE HOUSING – ISB 6.7L (2007.5–2018) (not for 5.9L).
Often Paired With (Cummins OEM)
- Front timing cover (gear cover): CUMMINS 4935569 OEM TIMING GEAR CASE FRONT COVER – ISB 5.9L/6.7L (2003–2018)
- Front crankshaft seal (front main seal) for 5.9L/6.7L: CUMMINS 3804899 OEM FRONT CRANKSHAFT SEAL – RAM 5.9L/6.7L (2003–2018)
- Front crankshaft seal service kit with installer: CUMMINS 3937111 OEM FRONT CRANKSHAFT SEAL SERVICE KIT – 5.9L CUMMINS (1989–2007)
- Gear housing / cylinder block alignment dowel: CUMMINS 3949326 OEM RING DOWEL – FRONT GEAR HOUSING/CYLINDER BLOCK ALIGNMENT – ISB 5.9L/6.7L (2003–2018)
- (Optional) Front cover gasket (gear cover to gear case) – confirm by VIN/ESN: CUMMINS 3918673 OEM GEAR COVER GASKET – 5.9L CUMMINS
Specifications for cummins 3970305
| Field | Value |
|---|---|
| Brand | Cummins Genuine OEM |
| Cummins Part Number | 3970305 (gear housing / timing gear case) |
| Supersedes / Cross Reference | Supersedes 3970303, 3970304; related casting 3970306 (verify by ESN). |
| Primary Automotive Fitment | 2003–2007 Ram 2500/3500, 5.9L ISB (24V common-rail) – front timing gear housing. |
| Industrial / Marine Fitment | Select 5.9L ISB/QSB Tier 3 engines (verify by engine serial number / ESN). |
| UPC | Not specified by manufacturer (no public UPC listed as of latest data). |
| GTIN | Not specified by manufacturer (enter internal GTIN if available). |
| Shipping Weight | Approx. 8.5 lb (Cummins lists ~8.23 lb; typical packaged weight ~8.6 lb). |
| Package Dimensions | Approx. 21.0 in L x 21.25 in W x 4.75 in H (typical boxed dimensions). |
| Configuration | Front timing gear housing / gear case – mounts to engine block; front cover bolts on separately. |
| Quantity | 1 per engine (sold individually) |
| E-Codes / Emissions | Designed for 5.9L ISB common-rail (2003–2007 light-duty diesel) and Tier 3 ISB/QSB 5.9L; confirm emissions family via ESN for industrial applications. |
| Prop 65 Warning | This product can expose you to chemicals including lead and other compounds which are known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov. |
FAQ
IS THIS THE FRONT COVER OR THE GEAR HOUSING?This part is the gear housing / timing gear case that bolts directly to the engine block and supports the front gear train. The flat outer timing cover that bolts to this housing is sold separately as Cummins 4935569.
WHAT VEHICLES DOES CUMMINS 3970305 FIT?
3970305 is the OEM front gear housing for most 2003–2007 Ram 2500/3500 trucks equipped with the 5.9L ISB common-rail Cummins. Always verify by VIN/ESN if you suspect engine swaps or mixed components.
DOES 3970305 REPLACE OTHER CUMMINS PART NUMBERS?
Yes. 3970305 commonly supersedes earlier gear housing numbers such as 3970303 and 3970304 on 5.9L ISB applications. You may also see casting 3970306 on used housings; confirm fitment by ESN for non-standard builds.
WHAT GASKETS AND SEALS SHOULD I REPLACE WHEN INSTALLING THIS HOUSING?
At minimum, replace the gear housing-to-block gasket (as specified by Cummins), the front crankshaft seal (Cummins 3804899 or the 3937111 service kit), and the timing cover gasket between the gear housing and front cover. Inspect alignment dowels and replace any worn units with Cummins 3949326.
WILL THIS FIT MY INDUSTRIAL OR MARINE 5.9L ISB/QSB?
Many Tier 3 5.9L ISB/QSB industrial and marine engines use 3970305, but Cummins built numerous variants. For non-automotive equipment, always confirm by engine serial number (ESN) and current part number in QuickServe or your Cummins service documentation before ordering.
IS THIS A GENUINE CUMMINS PART?
Yes. This is a brand-new genuine Cummins OEM gear housing with factory machining and sealing surfaces, sourced through CPP Diesel so you get OE quality instead of uncertain aftermarket castings.
