Yukon Gear Grizzly Locker For Ford 9in w/ 35 Spline Axles

The Yukon Grizzly Locker YGLF9-35 is a full-carrier mechanical locker for a Ford 9-inch rear end that has been upgraded to 35-spline axle shafts. It is the part people shop for when an open or worn limited-slip 9-inch keeps spinning one tire off the line, on a ledge or in mud, or when a stout build has outgrown the factory 28 or 31 spline shafts and needs a carrier to match heavier axles. Fits classic F-100, F-150 and Bronco housings, Mustang and Fairlane cars, and aftermarket 9-inch housings, as long as the third member and axles meet the specs below.

What the Grizzly Locker does in a Ford 9-inch

The 9-inch is a drop-out design: the ring gear, carrier and pinion live in a removable center section that bolts into the front of the housing, so the whole differential is built on the bench and slid in as one unit. The Grizzly replaces the open or posi carrier inside that center section. Under power it locks both 35-spline axles together so each tire gets full torque, and when one wheel needs to turn faster in a corner, the internal clutch teeth ride over each other and let that side unlock. Yukon builds the internals from 8620 steel and uses a tooth profile with a larger radius at the base, which it rates at up to 350 percent stronger than back-cut lockers. There are no clutch packs to wear out.

Symptoms that point to a locker upgrade

• One rear tire spins while the other sits still on a launch, a climb or a slick ramp.
• A tired factory or aftermarket posi that no longer pushes both tires, or chatters and binds.
• Broken spider gears or a cracked cross shaft in an open 9-inch carrier after hard launches or shock loads.
• Snapped 28 or 31 spline shafts that led you to 35-spline axles, which need a 35-spline carrier.
• Clunks and metal flakes in the gear oil from worn carrier internals, often alongside the 9-inch's known pinion support bearing wear.

How to confirm what you need before buying

Jack up the rear with the transmission in neutral and turn one wheel. If the other turns the opposite way, you have an open carrier. Pull the drain or fill plug and look for metal on the magnet, then check axle spline count: factory 9-inch shafts are 28 or 31 spline, and 35 spline only comes from aftermarket axles. Our Ford 9-inch rear end problems and rebuild cost guide covers the noises and wear points to inspect, and the ELocker vs Grizzly Locker comparison helps if you are deciding between a selectable and an automatic locker.

Fitment

This listing is the Ford 9-inch Grizzly for 35-spline axles, Yukon part YGLF9-35. Two details decide fitment, so check both before ordering:

• Bearing bore: Yukon states this unit requires a 3.250 in. dropout, and it uses 2.000 in. diameter carrier bearing journals. Third members with the smaller bearing bores will not accept it.
• Axles: it needs 35-spline shafts. Running stock 31-spline axles? Use the 31-spline Grizzly YGLF9-31 instead.

Yukon lists the 9-inch application across 1957-1987 Ford F-100 and F-150, 1966-1986 Bronco, Econoline vans, Fairlane, Falcon, Galaxie, Granada and more, but those vehicles left the factory with 28 or 31 spline axles, so the 35-spline version only fits once the axles and center section have been upgraded. If you are unsure, send us your case markings, bearing bore measurement and axle spline count and we will confirm. More 9-inch and axle parts are in our hard parts collection.

Install notes

Mount the center section on a stand, remove the old carrier, and transfer the ring gear with new bolts torqued to spec. Because the Grizzly needs a 3.250 in. case, it is a good time to replace carrier and pinion bearings; if your case is the Daytona-pattern design, the Daytona LM104911 master overhaul kit covers bearings, races and seal. Set carrier bearing preload and backlash with the threaded adjusters, then confirm the gear pattern. Changing ratio at the same time? The 3.50 ratio ring and pinion and the pinion depth shim kit pair well. Fill with 75W-90 or 85W-140 gear oil. A mechanical locker has no clutch packs, so limited-slip friction modifier is not needed. Expect some clicking and tire chirp in tight turns while the unit ratchets; that is normal locker behavior.

Will the YGLF9-35 fit my stock Ford 9-inch?

Only if the center section has the 3.250 in. bearing bore and you run 35-spline axles. Factory 9-inch shafts are 28 or 31 spline, so a stock rear needs aftermarket 35-spline axles, or the 31-spline Grizzly YGLF9-31 instead.

Do I need friction modifier with a Grizzly Locker?

No. The Grizzly is a mechanical locker with no clutch packs, so plain 75W-90 or 85W-140 gear oil is fine. Friction modifier is for clutch-type limited-slip units.

Is the Grizzly street friendly?

It is built for trail, off-road racing and drag use, and it works on the street, but you will hear clicking and feel the rear push in tight turns as the unit unlocks and relocks. That behavior is normal for an automatic locker.

What else should I replace when installing it?

Plan on carrier bearings, pinion bearings, a pinion seal and new ring gear bolts. If you change gear ratio, add a ring and pinion set and a pinion depth shim kit and set up the pattern from scratch.

How heavy is it to ship?

Yukon lists a shipping weight of about 20.5 lb for this unit, packed in an 11 x 11 x 11 inch box.