The 1310 series is the most widely used light-duty size in the catalog. These end yokes mount to a splined output shaft and accept a 1310 cross.
Series alone does not size an end yoke. Count the splines on your output shaft and measure across the spline tips, then match both figures on the part page.
An end yoke slides onto the splined output of a transmission, transfer case or differential and is retained by a nut on the shaft end. It presents the two ears the u-joint sits in, so the series governs which cross can be used while the spline data governs which shaft it fits.
Series 1310 is the volume size for domestic light trucks, vans and a great deal of performance work. Because so many different spline configurations share the 1310 joint envelope, always confirm spline count and spline diameter as well as the series.