Yukon Gear 8.8in Ford 3/4in Notched Cross Pin Shaft (0.750in / 85 and Older)
This is the small-diameter cross pin for the earliest Ford 8.8 rear axles: a notched 3/4 inch (0.750 in) shaft, Yukon Gear and Axle part number YSPXP-057, for 8.8 axles from the 1985 model year and older. The 8.8 first went into 1983 F-150 trucks, so this pin is for the early F-series, Bronco and mid-1980s passenger car housings that still carry the original small shaft. If you have a clunk on take-off, a pin with flat spots worn into it, or a broken pin after a hard launch, this is the replacement you need for those early carriers.
The cross pin, also called the pinion shaft or spider shaft, passes through the differential case and carries the two pinion (spider) gears. Torque from the ring gear goes through the case, into this pin, and out through the spider gears to the side gears and axle shafts. On the solid-axle 8.8 it does a second job: the axle shafts are held in by C-clips inside the carrier, and the cross pin is what keeps the axle shafts from sliding inboard and letting those clips fall out. A single lock bolt holds the pin in the case. If that bolt loosens or the pin breaks, the axle can work loose, so a damaged pin is a safety item, not just a noise.
Pull the cover, rotate one wheel and watch the spider gears. Remove the lock bolt and slide the pin out, then inspect it where the gears rode and check the spider gear bores for matching wear. A grooved pin always gets replaced, and worn spider gears usually go with it. Measure the shaft: this part is 0.750 in. The Ford 8.8 problems and rebuild cost guide covers the other wear points to inspect while it is apart, and our transmission versus differential noise guide helps confirm the clunk is in the axle.
Yukon lists YSPXP-057 for 8.8 inch Ford axles built in 1985 and earlier. From 1986 on, Ford moved to a larger 7/8 inch (0.875 in) shaft, which this pin does not replace. Because axles were swapped and rebuilt over the years, a 1986-or-later vehicle can carry an early carrier and the reverse can also be true, so measure the old pin or the bore in the case before ordering. This is a standard notched shaft for the open and Traction-Lok carriers. Drop-in lockers use their own cross pin; the Spartan Locker for the 8.8 includes one. If you are unsure, send us the year, VIN and axle tag and we will check it. More 8.8 parts are in our hard parts catalog.
If the axle has more than a clunk, such as a pinion bearing whine, pair the job with a master bearing kit so the axle only has to come apart once.
| Brand | Yukon Gear & Axle |
| Part number | YSPXP-057 |
| Fits | Yukon Gear 8.8in Ford 3/4in Notched Cross Pin Shaft (0.750in / 85 and Older) |
| Type | Differential Bushings |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Measure the pin with a caliper or micrometer. Yukon lists this 0.750 in pin for 1985 and older 8.8 axles; 1986 and newer axles generally use the 0.875 in pin. Axles get swapped, so measuring beats going by the vehicle year.
It is better to replace it. The bolt is the only thing keeping the pin, and therefore the C-clip axles, in place. Use thread locker and torque it to the factory spec.
If the old pin is grooved, the spider gear bores are usually worn too. Inspect them, and replace the gears and thrust washers if you see pitting, galling or looseness on the new pin.
Drop-in lockers ship with their own cross pin designed for the locker. Use the pin supplied with the locker, not this standard notched shaft.
Use the 75W-140 or 75W-85 gear oil your owner's manual lists for the axle. Add Ford's specified friction modifier if the axle has a Traction-Lok limited slip.
