Yukon Gear Cast Yoke For GM 8.5in w/ A 1350 U/Joint Size

If the rear of your Silverado, Tahoe, C1500, Blazer, Monte Carlo or Cutlass keeps dripping gear oil from the nose of the axle no matter how many pinion seals you install, the yoke is usually the real culprit. The Yukon Gear and Axle YY GM8.5-1350-C is a cast replacement pinion yoke for the GM 8.5 inch ten-bolt and the 8.6 inch rear that replaced it. It slides onto a 30-spline pinion and holds a 1350 series U-joint with straps, the clamp style many factory GM driveshafts use.

What the pinion yoke does in a GM 8.5 or 8.6 axle

Every bit of torque from the transmission reaches the ring and pinion through this yoke. The driveshaft's rear U-joint sits in the two ears and is clamped down by bolt-on straps, and the yoke itself is pulled tight onto the pinion splines by the pinion nut. The machined neck behind the ears is the running surface for the pinion seal, so a yoke worn in that spot leaks even with a brand-new seal. On this cast part the joint is held by straps rather than U-bolts, which is the key difference from the forged GM 8.5 yoke, which uses U-bolts. Pick the one that matches the retainers on your driveshaft.

Symptoms that point to the yoke

• Gear oil flung along the underside of the truck or car, coming from the pinion seal area
• A new pinion seal that starts weeping within weeks because the old seal wore a groove into the yoke neck
• A clunk on takeoff, or when shifting between drive and reverse, from loose pinion splines
• Driveline vibration that rises with road speed after a yoke was damaged by a seized U-joint or a bad removal
• Strap bolt threads in the ears that are stripped or keep backing out

How to confirm before ordering

Support the axle, unbolt the straps and drop the driveshaft. Grab the yoke and try to turn it back and forth against the pinion; any free play or a clicking feel means the splines or the pinion preload are no longer right. Wipe the seal surface clean and feel for a ridge. Measure the U-joint: a 1350 joint has 1.188 inch caps and a 3.625 inch span measured across the outside snap rings. If you find play in the pinion bearings themselves rather than just a worn yoke, plan on a full rebuild with a GM 8.5 Timken master bearing kit instead of only swapping the yoke.

Fitment

Yukon's application list for this yoke covers GM 8.5 inch rears in cars such as the 1970-1979 Nova, 1970s Chevelle and Monte Carlo, Camaro, Firebird, Impala, Caprice, Cutlass, Regal, Grand Prix and El Camino, plus C10, C1500, K1500, G-van, Blazer and S10 trucks. It also lists 8.5 inch front axles on 1977-1991 K-series trucks and the 8.6 inch rear in 1999-2017 Silverado and Sierra 1500 and 1999-2017 Tahoe, with shorter runs for the Yukon, Avalanche, Escalade, Express and Savana 1500, Colorado, Canyon, Trailblazer, Envoy and Hummer H3. GM built several pinion and joint combinations over these years, so confirm a 30-spline pinion and a strap-style 1350 joint on your vehicle, or send us the year, model and VIN and we will check it. Other GM axle hardware is in our hard parts section.

Install notes

• Scribe a line across the driveshaft and the old yoke before you take it apart so the shaft goes back in the same phase.
• Before removing the pinion nut on a crush-sleeve axle, record the pinion rotating torque with an inch-pound torque wrench. Do not crank the nut down past that reading; over-crushing the sleeve overloads the pinion bearings. A crush sleeve eliminator kit replaces the sleeve with solid shims if you would rather set preload once.
• Fit a new pinion seal every time the yoke comes off, and coat the seal lip with gear oil.
• Torque the strap bolts evenly, recheck the gear oil level with 75W-90 gear oil, and add friction modifier if the axle has a clutch-type posi.

Does this cast yoke use straps or U-bolts?

Straps. It is built for a 1350 series U-joint held by bolt-on straps. If your driveshaft uses U-bolts, the forged GM 8.5 yoke YY GM8.5-1350-F is the U-bolt version.

What size U-joint does it take?

A 1350 series joint with 1.188 inch bearing caps and a 3.625 inch span between the outside snap rings.

Will it fit my 2010 Silverado 1500 rear axle?

Yukon lists the 2009-2017 GM 8.6 inch rear in Silverado and Sierra 1500, as long as the pinion has 30 splines and the driveshaft uses a strap-style 1350 joint. Send us your VIN if you want it checked.

Cast or forged - does it matter?

Both share the same 1350 joint size and 30-spline bore. Cast is a solid choice for stock or mildly modified street vehicles. The forged yoke is stronger for hard launches, oversize tires and heavy towing.

Do I need anything else when I replace the yoke?

A new pinion seal, a new pinion nut if the old one is damaged, and fresh gear oil. On a crush-sleeve axle, measure pinion turning torque before taking the old yoke off so you can restore preload.