Vehicle input shafts are disclosed. The vehicle input shafts include a bearing boss, a spline portion, a cylindrical shaft body portion and a drive end. The spline portion includes spline teeth and spline grooves that do not exit directly onto the shaft body. Instead, the spline grooves include blend out fillets that interrupt the spline grooves by providing additional material near the shaft body. The bearing boss includes an increased diameter at a central point along its axial length and decreased diameters at its first and second boss ends.