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Ordering a u-joint by vehicle is the fast way to get the wrong one. Driveshafts get swapped, yokes get changed during transmission and transfer case swaps, and a previous owner may have built a shaft with a conversion joint in it. The series number is the language every driveline shop uses, and it comes down to two measurements you can take in the driveway with a caliper.
The Two Measurements That Matter
- Bearing cap diameter — the outside diameter of the cup.
- Span — the distance across two opposite caps, measured to the outer edges. On outside-snap-ring joints, measure across the cap ends. On inside-snap-ring and factory injected-plastic joints, measure the yoke ear-to-ear dimension the caps sit in.
The 1310 and 1330 share a cap size but not a span. The 1330 and 1350 share a span but not a cap size. That is exactly why people mix them up.
| Series | Cap Diameter | Span | Where You See It |
|---|---|---|---|
| 1310 | 1.062 in (1-1/16) | 3.219 in | Most stock half-ton and Jeep shafts, light transfer case and pinion yokes |
| 1330 | 1.062 in (1-1/16) | 3.625 in | Ford half-ton and some GM pinion yokes, older Dana 44 yokes |
| 1350 | 1.188 in (1-3/16) | 3.625 in | 3/4 and 1-ton trucks, TH400 and many performance slip yokes, Dana 60/70 |
| 1410 | 1.188 in (1-3/16) | 4.188 in | Heavy 1-ton, Dana 60/70/80 heavy-duty yokes |
Measure twice. A 1310 cap and a 1350 cap are only an eighth of an inch apart, and a tape measure will not tell them apart reliably. Use a caliper.
Strength: What Stepping Up Actually Buys You
Each step up the series list is a bigger cross with bigger trunnions and more needle bearing area. The 1350 is a major jump over a 1310 because both the cap and the span grow. Torque capacity scales with that, and so does tolerance for running angle and shock load.
On a stock half-ton with stock tires, a quality 1310 is not the weak link and never has been. Problems start when you add some combination of:
- 35-inch or larger tires
- Low gears (4.56 and up) and a locker, which multiply torque into the shaft
- A lift that increases operating angle
- Towing heavy on a shaft that was sized for an empty truck
If you have two or more of those and you are already replacing a yoke or building a shaft, go to 1350. If you have one and the joints are healthy, a quality non-greaseable 1310 is fine.
Greaseable vs Non-Greaseable
A grease fitting means a drilled passage through the cross, which removes material from the strongest part of the joint. Solid-cross non-greaseable joints are stronger and come pre-packed. Greaseable joints are serviceable and better for a truck that wades water often, as long as somebody actually greases them. On a trail rig with a locker and big tires, we run solid-cross joints. On a work truck that sees mud and creeks every week, greaseable with a disciplined maintenance schedule.
Conversion Joints
A conversion u-joint has two caps of one series and two of another, letting you join a 1310 yoke to a 1350 shaft or similar. They are common after transmission and transfer case swaps. They work, and they are fine for moderate duty, but the joint is only as strong as its smaller side. If you are building a shaft for a hard-use truck, the better fix is to change the yoke so both ends match.
Common Swap Scenarios
Transmission swap with a new slip yoke
When you swap to a TH400, 4L80E or a different transfer case, the slip yoke spline count changes and often the u-joint series changes too. Many aftermarket slip yokes are 1350 regardless of what the factory used. Measure the shaft before ordering. Our slip yoke buyer's guide covers spline counts by transmission.
Lifted Jeep or half-ton
The rear pinion yoke and transfer case output are usually 1310. Going to a double-cardan shaft for angle often means a 1310 CV on stock yokes, or a 1350 shaft with a new pinion yoke and output yoke or flange. Weigh the cost of the yokes before choosing.
Pinion yoke replacement
If a pinion yoke is worn at the seal surface or the ears are wallowed out, replace it with the same series unless you are changing the shaft. Torque the pinion nut to spec and do not crush a solid-spacer setup by over-tightening.
Signs a Joint Is Done
- Clunk on shifting into drive or reverse
- Squeak that tracks wheel speed at low speed
- Vibration that gets worse with speed
- Rust dust around the caps, or any play when you twist the shaft against the yoke by hand
Full diagnosis and costs are in our u-joint replacement guide, and the press-out procedure is in how to replace a u-joint.
Install Mistakes That Kill New Joints
Most u-joints that fail early were damaged going in. Three habits cause nearly all of it:
- Hammering the yoke ears. Beating caps out with a hammer distorts the ears. The new joint binds or runs loose and fails in weeks. Use a press or a proper puller.
- Dropped needle bearings. Pressing a cap in with a needle lying across the bottom ruins the joint instantly. Go slow and check that the cross moves freely before setting the clips.
- Skipping the phasing marks. Mark the slip yoke and shaft before separating them. Reassembling a two-joint shaft out of phase causes a vibration that no balancing will fix.
After the clips are in, a sharp tap on the yoke with a brass hammer relieves the preload and frees a stiff joint. The joint should articulate smoothly in every direction with no notchy spots.
Shop Yokes and U-Joint Tools
Match the Yoke, Then the Joint
Slip yokes, pinion yokes, transfer case yokes and u-joint pullers ship from our shop. Transmission hard parts for the swap are available at our sister store.
Shop Driveline Parts → Core Transmission Parts →FAQ
Can I tell 1310 from 1330 by looking at it?
Not reliably. They use the same 1-1/16 inch cap. Only the span differs, 3.219 inches for 1310 versus 3.625 inches for 1330. Measure across the caps.
Is 1350 always better than 1310?
Stronger, yes. Better, only if the rest of the driveline needs it. On a stock truck it adds cost and requires matching yokes on both ends for no real gain.
Are conversion u-joints safe?
For moderate duty, yes. They are as strong as their smaller side, so on a heavy-use build the better fix is a yoke that matches the shaft.
Do inside and outside snap ring joints interchange?
Not directly. The yoke determines which style fits. Factory GM shafts with injected plastic retainers take inside-clip service joints.