Serial breaks:
231
508911999 & Below, 508912001 & Above
325 & 328
514011001 - 514012999 (Rubber Track Version Only), 511820001 & Above, 514013001 & Above, 516611001 & Above, 232311001 & Above, 232411001 & Above, Starting at 234111001 & Above there is a switch to the 12B/12T sprocket known as 6813372 (different from ours)
331, 331-E, 334
511920001 & above, 511920001 & above, 512911001 - 512912999, 512913001 & above, 511711001 & above, 516711001 & above, 232511001 & above (must verify bolt holes), 232711001 & above (must verify bolt holes), 232611001 & above (must verify bolt holes)