USA Standard Replacement Ring & Pinion Gear Set For Dana 80 in a 5.38 Ratio

The ZG D80-538 is a USA Standard Gear 5.38 ring and pinion for the Dana 80. That is the 11.25 inch full-floating rear axle under 1-ton dually and chassis-cab trucks. USA Standard's fitment list includes 1988-1997 Ford F-350 and F-Super Duty, 1999-2015 F-350 Super Duty, 1999-2005 F-450 Super Duty, E-350 and E-450 vans, 1994-2002 Dodge Ram 2500 and 3500, 1995-1998 B3500 vans, 1990-2000 Chevrolet and GMC K3500 and C3500, the 1991-2002 C3500 HD, Express 3500 vans, P30 and P3500 chassis, and the 2003-2009 C4500 Kodiak. A 5.38 is a deep gear. It is built for trucks on 40 inch and larger tires, wreckers, campers and flatbeds that live at full weight, or a dually that has been re-tired and can no longer pull its load up a grade.

What the ring and pinion does in a Dana 80

The Dana 80 carries its load on the axle tubes through full-floating hubs, so the ring and pinion handle only torque. This set has an 11.25 inch ring gear held by 12 bolts and a 37-spline pinion, matching the factory pinion yoke spline. A 5.38 ratio spins the driveshaft 5.38 times per tire revolution. On a 40 inch tire at 65 mph, that is about 2,937 engine rpm in a 1:1 gear (mph x ratio x 336 / tire diameter). Overdrive brings that down, but this is still a working gear, not a highway economy gear. The same housing can carry 35-spline or 37-spline axle shafts. The axle spline count has nothing to do with this gear set, but it matters when you pick a carrier.

Symptoms that call for new Dana 80 gears

• Whine at cruise that changes pitch between pulling and coasting, louder when the truck is loaded.
• A grinding rumble that holds steady off-throttle. That is usually pinion or carrier bearings, which on a Dana 80 often take the gears with them once they get loose.
• Chipped or spalled teeth, or a ring gear damaged by a shock load while towing.
• Gear oil on the cover, pinion seal or hub seals, followed by heat and noise.
• A truck that will not hold its top gear with a load after a move to taller tires.

How to confirm before you buy

A Dana 80 has a 10-bolt asymmetrical cover and an 80 cast into the housing. A Dana 70 or a Sterling 10.5 looks similar from a distance, so check the casting before ordering. Confirm the noise is in the axle and not the transmission. On 1994-2002 Rams, our 47RE noise diagnosis guide covers the driveshaft-off test that separates the two. Then decide on ratio. Compare your current ratio, read from the axle tag, to the rpm you want at your normal cruising speed and tire size.

Fitment and carrier

USA Standard notes that this gear fits the 4.10-and-up carrier. A Dana 80 that came with 3.54 or 3.73 gears has the 3.73-and-down carrier and will need a new carrier for a 5.38. That makes this the right time for a locker or posi. The Dana 80 Dura Grip for 35-spline 4.10-and-up gears and the Dana 80 steel spool for 4.10-and-up both match this ratio. If you are staying closer to stock, see the Dana 80 3.73 set, which uses the smaller carrier. Send us your year and VIN, plus the numbers on the axle tag, and we will confirm the fit.

Install notes

Yukon's setup chart for the Dana 80 lists 25-40 in-lb of pinion bearing preload with new bearings, 10-16 in-lb with used bearings, 0.006-0.011 in. of backlash on 5-cut gears, 175 ft-lb on the ring gear bolts and 90 ft-lb on the bearing caps. Carrier bearing preload comes from shims, so the case has to be spread slightly to set and remove the carrier. A housing spreader keeps you from prying on the housing. Replace all bearings and races. The pinion race outside diameter decides the install kit. 1998-and-newer Fords use the 4.375 inch race and take the YK D80-B master kit. The 4.125 inch race axles take the ZK D80-A kit.

Fill with the gear oil your owner's manual calls for. Most Dana 80 trucks specify 75W-90 or 75W-140, and the heavier oil suits trucks that tow. Break the gears in lightly. Drive 15-20 easy miles, let the axle cool, skip towing for 500 miles, and then change the oil. Have the ratio and tire size reprogrammed so the speedometer and transmission shifts are right.

Will this 5.38 set fit my Dana 80 that has 3.73 gears now?

Only with a different carrier. USA Standard lists this gear for the 4.10-and-up carrier, and factory 3.54 and 3.73 axles use the 3.73-and-down carrier. Plan on a 4.10-and-up carrier, posi or spool with these gears.

Does it matter if my axles are 35 or 37 spline?

Not for the gear set. The pinion is 37-spline in every Dana 80, and the ring gear bolts to any 4.10-and-up carrier. The axle spline count only decides which carrier, posi or spool you buy.

Which install kit do I need?

It depends on the pinion race outside diameter. 1998-and-newer Ford Dana 80s use a 4.375 inch race. Most other Dana 80s use 4.125 inch. Buy the master overhaul kit that matches, and measure the old race if you are unsure.

Is 5.38 too low for highway driving?

On stock-size tires, yes. It will rev high at highway speed. A 5.38 makes sense on 40 inch or larger tires, or on trucks that work at full weight and rarely run fast. Run the mph x ratio x 336 / tire diameter math with your overdrive before choosing.

What is the difference between USA Standard and Yukon gears?

Both come from the same company. USA Standard is the replacement line, built to OEM specification. Yukon is the high-performance line. Both share the Dana 80 dimensions: 11.25 inch ring gear, 12 bolts and a 37-spline pinion.