Yukon Gear Grizzly Locker / Ford 10.25in & 10.5in w/ 35 Splines

Yukon Gear Grizzly Locker for Ford 10.25 Inch and 10.5 Inch Differential with 35 Spline Axles

Part number YGLF10.25-35 is an automatic locking differential built for Ford 10.25 inch and 10.5 inch Sterling rear axle housings equipped with 35 spline axle shafts. The YGLF10.25-35 Grizzly Locker delivers true 100 percent lockup under torque across a massive range of Ford applications including F-250, F-350, E-Series vans, and Excursion models. Whether you are navigating off-road terrain, pulling heavy loads, or simply need maximum traction, the YGLF10.25-35 is engineered to outperform limited-slip units in demanding conditions. The locker disengages smoothly during normal turns on pavement for everyday drivability.

Features and Benefits

• Fits Ford 10.25 inch and 10.5 inch Sterling rear differentials with 35 spline axles
• Full mechanical lockup activates automatically under throttle torque
• Precision-machined steel construction for heavy-duty load capacity
• Direct drop-in installation into the existing carrier bore
• Disengages on light throttle during turns for normal street behavior
• Compatible with gear ratios from 3.55 and up
• Covers an extensive range of Ford truck, van, and SUV applications
• Backed by Yukon Gear manufacturer limited warranty

Vehicle Fitment

Specifications

What Is Included

• One Grizzly Locker differential assembly (YGLF10.25-35)
• All internal locking hardware and cross pins
• Installation instruction sheet

Frequently Asked Questions

Does YGLF10.25-35 affect my vehicle warranty under federal law?
Under the Magnuson-Moss Warranty Act, your factory warranty cannot be voided simply for installing an aftermarket differential. The dealer must prove the aftermarket component directly caused the specific failure being claimed.

How do I confirm I have a 10.25 inch versus a 10.5 inch Ford axle?
The 10.25 inch axle was used in older F-250 and E-350 models through the 1990s. The 10.5 inch Sterling axle appears in 1999-and-newer Super Duty trucks. Both use the same YGLF10.25-35 carrier. The ring gear diameter measurement from the center of the gear bolt circle will confirm your housing size.

Will YGLF10.25-35 work with my current ring and pinion ratio?
Yes, as long as your ratio is 3.55 or numerically higher. This locker drops into the standard carrier bore without requiring you to change the ring and pinion.

What kind of ratcheting noise should I expect on turns?
Mechanical lockers like YGLF10.25-35 produce a clicking or ratcheting sound during slow, tight turns. This is normal operation as the cams disengage to allow differentiation. The sound is more pronounced on dry pavement during sharp turns.

Is professional installation required?
Yukon Gear strongly recommends professional installation. Proper carrier bearing preload and ring gear backlash must be set to factory tolerances using dial indicators and pattern compound to ensure long component life.

Can I use synthetic gear oil with YGLF10.25-35?
Yes. Full synthetic 75W-140 or 80W-90 gear oil meeting Ford specification is compatible. Do not use limited-slip friction modifier, as YGLF10.25-35 is not a clutch-type unit.

Will this locker affect my tow rating?
YGLF10.25-35 does not reduce your vehicle tow rating. In fact, the improved traction can benefit towing on loose or slippery surfaces. Ensure your vehicle is otherwise in factory operating condition.

What warranty does the YGLF10.25-35 carry?
Yukon Gear provides a manufacturer limited warranty against defects in materials and workmanship. Warranty is void if the product was improperly installed or used outside its designed application.

Installation Instructions

1. Lift and support the vehicle safely. Drain the differential fluid completely.
2. Remove rear axle shafts by unbolting the retainer flange hardware.
3. Remove the differential cover and thoroughly clean the mating surface.
4. Mark and remove the carrier bearing caps. Note orientation for reinstallation.
5. Remove the existing carrier assembly from the housing.
6. Press off the ring gear and carrier bearings from the old carrier.
7. Transfer the ring gear onto the YGLF10.25-35 Grizzly Locker using a press and proper adapters.
8. Install new carrier bearings onto the Grizzly Locker assembly.
9. Set the assembled Grizzly Locker into the housing and install bearing caps finger-tight.
10. Adjust ring gear backlash with shims to 0.005 to 0.009 inch. Confirm with a dial indicator.
11. Check the gear contact pattern with marking compound and make shim corrections as needed.
12. Torque bearing cap bolts to the Ford factory specification.
13. Install the differential cover with new sealant or gasket and torque to spec.
14. Reinstall axle shafts and retainer hardware. Torque to factory spec.
15. Fill the differential to the correct fluid level and road-test for leaks.

Proposition 65 Warning: This product can expose you to chemicals including lead, which is 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.