A round bore end yoke mounts on a plain shaft and takes its drive from a key rather than from splines. It appears on PTO drives, industrial equipment and older applications.
Order by bore diameter and keyway size together. A round bore that fits the shaft but has the wrong keyway will not transmit torque safely.
Where a splined yoke shares load across every spline, a round bore yoke concentrates it on a single key. That makes the key and keyway dimensions as important as the bore itself, and it is why these yokes are usually specified for lower-speed industrial and PTO drives rather than high-torque automotive drivelines.
Measure the shaft diameter and the keyway width and depth before ordering. If the yoke is also clamped or pinned, note that as well.