Yukon Gear Dana 44 IFS Outer Stub Axle Replacement
Ford's Twin-Traction Beam front end puts a Dana 44 under a lot of late-1980s Broncos and F-Series 4x4s, and the short outer stub shaft at each wheel is a part that twists, wears its splines or breaks when big tires and hard launches are involved. This Yukon Gear and Axle YA D39906 is a new outer stub axle for the Dana 44 TTB (Yukon calls it Dana 44 IFS) front axle: 19 splines, 9.80 inches long, built for a 5-760X U-joint.
On the TTB, each front wheel is driven by two shafts joined by a U-joint at the steering knuckle. The inner shaft comes out of the differential (or the slip yoke on the long side) and the short outer stub passes through the spindle to the hub. The splined end of the stub engages the locking hub or drive flange, and the stub rides in a needle bearing pressed into the back of the spindle. Each time you turn the wheel in 4WD, the U-joint at the knuckle swings and the stub carries full axle torque at an angle. When the stub splines wear or the shaft twists, the hub can no longer lock solidly and the needle bearing behind it starts to wear out.
Lift the front, lock the hubs and put the transfer case in 4-high with the transmission in park. Try to rotate each front tire by hand. A tire that turns, or a clunk before it stops, means lash somewhere between the differential and the wheel. Pull the hub and inspect the stub splines and the hub clutch ring together, because worn hub parts and worn stub splines tend to go together. Next, remove the spindle and check the U-joint at the knuckle and the needle bearing in the spindle. A clicking noise in turns that goes away driving straight usually points to the U-joint, which you can replace with a U-joint press kit without changing the stub. Our Ford TTB front axle problems guide covers beam bushings, ball joints and the other common TTB failures.
Yukon lists this stub for the Dana Spicer 44 IFS (TTB) in the 1988-1991 Ford F-150 and Bronco, the 1980-1988 F-250 and the 1980-1985 F-350. Fords from these years can have either a Dana 44 or the heavier Dana 50 TTB, and the Dana 50 uses different shafts. Check the axle tag or casting before ordering. Earlier and later F-150s and Broncos are not on Yukon's list, so compare length (9.80 inches), spline count (19) and U-joint size (5-760X) with your old stub, or send us the year and VIN. Browse more axle and driveline hard parts here.
Top off the front differential with 75W-90 gear oil after the job. A replacement stub pairs well with new hubs if the originals have worn clutch rings.
| Brand | Yukon Gear & Axle |
| Part number | YA D39906 |
| Fits | Yukon Gear Dana 44 IFS Outer Stub Axle Replacement |
| Type | Axles |
| 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 not on Yukon's fitment list, which covers the 1988-1991 F-150 and Bronco, 1980-1988 F-250 and 1980-1985 F-350 with the Dana 44 TTB. Measure your stub (9.80 in. long, 19 splines, 5-760X U-joint) or send us your VIN and we will check.
Read the tag on the differential or the cast numbers on the carrier housing. Ford used both in F-250 trucks during these years, and Dana 50 shafts are different, so this stub only fits the Dana 44.
A 5-760X series U-joint. Install a new joint when you install the stub instead of reusing the old one.
It is an outer stub, which is the short shaft that goes through the spindle to the hub. Yukon sells it under one part number for the outer stub position; compare it with your old stub before you install.
Replace the spindle needle bearing and seal, the U-joint, and the wheel bearing seals. If your locking hub has worn clutch rings, replace the hub too or the new splines will wear.
