Let me clarify - I may have misled you. A geartrain failure to us was where the part failed on it's own. Meaning it did not fail due to restricted cooler flow, or some other failure that reduced or shut off the fluid supply. Those "failures" generally came from trucks hauling way past Max GVWR or beyond. And our fleet testing showed that even when overloaded - if the fluid was replaced at certain intervals the OD would live. Most owners were not doing that.

Every vehicle investigation we did where we had the failures came from an overloaded truck and the vast majority of those never were properly maintained. There were a host of other issues that were resolved in the OD transmissions that kept engineering busy - the addition of steel planetaries in the trans, different spline angles for the diesel OD sun gear, steel instead of powder metal for the direct hub spring seat, revised OD piston, larger input shaft. Today the Reman program rarely sees an overdrive failure. Thousands of units sold with very few warranty returns.