Not using the factory ZF oil could be why you have this long term damage. These boxes are sensitive to oil changes due to differences in temps and pressures. Even more so when using aftermarket trans coolers. Factory oil is by far the best and any external trans cooler needs to be run in series with the factory style heat exchanger (however upgrade the heat exchanger to a stronger unit) and fittings and lines need to be the same diameter as factory. To answer your question, the shorter gears may help the box a little. But if the damage is done, death is still enevitable.