Yukon Gear Replacement Left Hand axle For Dana 80 / 35 Spline / 38.74in / 8 X 4.02in Bolt...

Ford F-350 dually owners towing a fifth-wheel or a loaded flatbed are the people who end up shopping for this part: a driver-side Dana 80 shaft with twisted splines, a cracked flange, or bolt holes that were wallowed out after the flange ran loose. Yukon Gear and Axle part YA D47847-4 is a new left-hand replacement shaft for the Dana 80 rear, 35 spline and 38.74 inches long, with the flange bolt pattern Yukon lists as 8 x 4.02 inches. Yukon's own description ties it to the Dana 80 under 2000-2002 Ford F-350 trucks with dual rear wheels.

What the left shaft does in a Ford Dana 80

The Dana 80 is built only as a full-floating rear axle. The hub rides on its own bearings on the end of the axle tube, so the shaft is not holding the truck up. Its single job is torque: the 35 splines on the inboard end engage the driver-side side gear in the carrier, and the flange on the outboard end bolts to the wheel hub. Every pull up a grade with a trailer twists that shaft, and a shaft that has started to yield will not straighten itself back out. The left side matters on its own because the two shafts are different lengths on most axles; a right-hand shaft will not substitute.

Symptoms that point to the left shaft

• A clunk from the driver-side rear on take-off or when the load changes, with the carrier itself checking out tight.
• Gear oil weeping from the driver-side flange, which on a full-float axle usually means flange gasket or loose bolts rather than a hub seal.
• Splines that look spiraled instead of straight once the shaft is pulled, a sign it has been overloaded.
• The truck will not move with the left wheel on the ground spinning freely, the typical result of a broken shaft with an open carrier.
• Sheared or stretched flange bolts and elongated holes in the flange.

How to confirm before you buy

Because the axle is full floating, you can pull the left shaft without removing the wheel bearings. Remove the flange bolts, slide the shaft out, and inspect it on a bench: look down the splines for twist, roll it on a flat surface to check for a bend, and check the flange for cracks around the bolt holes. Count the splines and measure overall length; this shaft is 35 spline at 38.74 inches. If the noise turns out to be a growl rather than a clunk, the pinion or carrier bearings are the more likely cause, and our Dana 80 rear axle problems and rebuild cost guide covers that diagnosis. The differential vs transmission noise guide helps when you are not sure where the sound starts.

Fitment

Yukon's product text calls this the left shaft for the Dana 80 in 2000-2002 Ford F-350 with dual rear wheels. Its fitment table is broader, listing 1999-2000 and 2001-2015 F-350 Super Duty rear applications, and one of those rows labels the differential as a 37-spline Ford Dana 80 even though this shaft is 35 spline. Many Super Duty pickups were built with a Sterling 10.5 rear instead of a Dana 80, so confirm the axle first: the Dana 80 has a 10-bolt asymmetrical cover and an 80 cast into the housing. Then count your shaft's splines and measure its length. If anything does not match, send us the year and VIN before ordering. More rear axle hardware is in our hard parts category. If your truck needs the 37-spline, 40-inch Dana 80 shaft instead, see Yukon YA D47852-1.

Install notes

• Clean the hub face and the shaft flange completely and use a new flange gasket; old gasket material left behind is the most common reason a new shaft leaks.
• Feed the shaft in straight and rotate it slightly so the splines find the side gear without being forced.
• Tighten the flange bolts evenly in a cross pattern to the torque in your Ford service manual, and recheck after the first loaded trip.
• If the shaft broke, drain the axle and pull the cover to look for fragments. A worn carrier is a good reason to rebuild now: Ford Dana 80s built from 1998 on may use the larger pinion race in the USA Standard 4.375 in OD Dana 80 overhaul kit, while earlier axles take the 4.125 in OD kit. Measure the race before ordering.
• A Yukon Hardcore Dana 80 cover is worth adding while the axle is open, and refill with the gear oil grade your owner's manual lists, plus friction modifier if the axle has a clutch-type limited slip.

Which side is this shaft?

YA D47847-4 is the left-hand rear shaft, the driver side on a US-market Ford. It is sold as a single shaft.

How do I know my truck has a Dana 80 and not a Sterling 10.5?

Look at the cover and the housing. A Dana 80 has a 10-bolt asymmetrical cover and an 80 cast into the housing. Many Super Duty pickups use the Sterling 10.5 instead, which takes different shafts.

My truck is listed in the fitment table but my old shaft has 37 splines. Will this work?

No. This shaft is 35 spline and must match the side gear in your carrier. Yukon's table includes a row labeled 37 spline, so always count the splines on your old shaft and measure its length (38.74 inches) before ordering.

Do I need to remove the wheel bearings to install it?

Not normally. The Dana 80 is full floating, so the shaft comes out after the flange bolts are removed. Replace the flange gasket and clean the mating faces.

Should I replace both sides at once?

Only if the right shaft also shows twist, bending or flange damage. Inspect it the same way; there is no need to replace a straight, clean shaft.