The sway bar end link sets are not measured by the bolt length.
Kit #9.8122 measurement of 2.55” is for the distance between the control arm and the sway bar. After you add the outer 5/8” top and bottom bushings, nut, and washers, the assembly will be over 4 inches long.
The bolt length of kit number #9.125 will be over 6” and will swing your sway bar ends into the axle.