When it comes to stock replacement applications, finding the right U-joint is as easy as using the basic Make/Model search on SummitRacing.com. But, if your driveline has been modified, choosing the right part can be challenging.

You’ll need to measure your U-joint to find its series or style. Most U-joints come in one of two configurations, and they’re measured in two different ways. To get started, grab a quality pair of calipers and measure the bearing cap diameter. Next, remove two opposing bearing caps and seals, and then reinstall the bearing caps on the cross. If your U-joint has four plain bearing caps (with the lock rings located on the outside end of the bearing caps), simply measure the overall width of the U-joint. On the other hand, if your U-joint has the lock-rings located near the inside end of the bearing caps, measure the distance from the inner edge of one lock-ring groove to the same point on the opposite bearing cap. Finally, measure the thickness of two lock rings and add that to your first measurement. In both cases, your measurement should be slightly less than the width dimension (O or I) shown in the series/style table below.

If you need assistance selecting the right U-joints—including conversion U-joints that work on a driveshaft of one series and yoke of another—you’ll need to know things like lock location, cap diameter, U-joint width, and grease fitting location (if any).

U-joints with Outside Locks              Bearing Cap
Series/Style           Width (O)              Diameter (D)

1300                              2.935″                        1.063-1.064″
1310                               3.218″                        1.063-1.064″
1330                              3.622″                        1.063-1.064″
1350                              3.622″                        1.188″
1410                              4.187″                         1.188″


U-joints with Inside Locks                Bearing Cap
Series/Style           Width (I)               Diameter (D)

1310-WJ                       2.188″                       1.188″
1485-WJ                      2.918″                        1.375″
S44/GM 3RL              2.563″                        1.125″
1310                              2.343″                        1.063-1.064″
Cleveland R55            2.563″                        1.188″

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Author: Dave Matthews

Dave Matthews was a mechanic for the U.S. Army, a Ford dealership, and served for many years as a fleet mechanic for construction companies. Now a technical content producer at Summit Racing, Dave has spent decades working on everything from military vehicles to high performance race machines.