2005 Kawasaki KAF400 Mule 600 and Mule 610 4x4 Service Manual, Page 276Get this manual
12-14 BRAKES Brake Drums
Insert new cotter pin [A]
When inserting the cotter pin, if the slots in the nut do not align with the cotter pin hole in the axle shaft, tighten the nut clockwise [B] up to next alignmentIt should be within 30 degreeLoosen once and tighten again when the slot goes past the nearest hole