Yukon Gear High Performance Gear Set For Dana 70 in a 3.73 Ratio
A Dana 70 rear that howls at highway speed, or a heavy-duty Ram, Ford or older GM one-ton that now runs a different tire size than it left the factory with, usually ends up needing a new ring and pinion. This Yukon Gear & Axle set, part number YG D70-373, is a 3.73 ratio replacement for the Dana 70 with a 10.50 in. ring gear, a 29-spline pinion and a 12-bolt ring gear pattern.
The pinion takes driveshaft rotation and the ring gear turns it 90 degrees into the carrier and axle shafts. At 3.73 the driveshaft turns 3.73 times for every turn of the tires. In a full-float Dana 70 those two gears carry every pound of payload and trailer you put behind the truck, which is why the 70 uses a bigger 10.5 in. gear than the Dana 60 and why pinion bearing preload and gear contact pattern are so critical. A 3.73 is a common middle ratio for these trucks: lower RPM on the highway than a 4.10, more pull than a 3.54.
Bearing noise and gear noise sound alike, so pull the cover and look. If the teeth are clean and only the bearings are tired, a master bearing kit may be all you need. If the teeth are scored or you are changing ratio, gears are the fix. Read the axle tag or count ring and pinion teeth to know your current ratio, and use our re-gear after bigger tires guide to decide whether 3.73 is the right target for your tire size. Our Dana 70 problems and rebuild guide covers the other common failures.
Yukon lists this set for the Dana Spicer 70 with a 10.50 in. ring gear, 29-spline pinion and 12 ring gear bolts. The Dana 70 was used under 1994-2002 Ram 2500 and 3500 trucks, heavy-duty Ford F-250, F-350 and E-series vans before the 10.25 took over, and some early GM one-tons, but the axle came in several versions. The 70-U and 70HD use different pinion bearings, and some trucks of the same year got a Dana 80 instead. Match the axle tag, pinion spline count and ratio before ordering, or send your year and VIN and we will confirm. More parts for this axle are in hard parts.
A new gear set means a full setup: pinion depth, pinion bearing preload, backlash and carrier bearing preload. Yukon's set-up chart for the D70 gives an OEM pinion shim of 0.061 in., 22-35 in-lb of preload on new pinion bearings, 0.006-0.011 in. backlash, 110 ft-lb on the ring gear bolts and 80 ft-lb on the caps. The Dana 70 sets pinion preload with shims rather than a crush sleeve, so plan on several trial assemblies. A pinion depth setting tool takes much of the guesswork out of the first pass.
Install new bearings with the gears. For a second-generation Ram, the 1994-2002 Ram Dana 70 master install kit covers bearings, seal and shims; for a 70-U axle use the YK D70-U overhaul kit. A worn yoke will chew up a new pinion seal, and the 29-spline 1410 yoke matches this pinion. Fill with 75W-90 or 75W-140 GL-5 (add friction modifier if you run a clutch-type limited slip) and follow the ring and pinion break-in procedure: Yukon calls for light driving at first, at least 500 miles before towing, and an oil change at 500 miles.
| Brand | Yukon Gear & Axle |
| Part number | YG D70-373 |
| Fits | Yukon Gear High Performance Gear Set For Dana 70 in a 3.73 Ratio |
| Type | Final Drive Gears |
| 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.
It is built for the Dana 70 with a 10.5 in. ring gear and a 29-spline pinion. Many 1994-2002 Ram 2500 and 3500 trucks use that axle, but some 3500s got a Dana 80. Check the axle tag or send your VIN and we will confirm.
Usually not on a Dana 70, but confirm that your current carrier accepts a 3.73 ring gear before ordering. If you are adding a limited slip at the same time, choose one rated for the 3.73 ratio and your axle spline count.
Replace all pinion and carrier bearings, races, the pinion seal and ring gear bolts. A master install kit covers those, and a new yoke is worth it if the seal surface is grooved.
Use 75W-90 or 75W-140 GL-5. Drive lightly for the first 15 to 20 miles and let it cool, avoid heavy acceleration for 100 miles, do not tow for 500 miles, and change the oil at 500 miles.
Only with a dial indicator, an inch-pound torque wrench, a bearing puller and press, and patience. The Dana 70 uses shims for pinion preload, so most installers pay a shop that does gear setups.
