It amazes me how the shaft managed to break. Gearbox oil pressure, main and standbye, is not very high and I would not have thought that it would put any undue torque on the driveshaft. The early Pumas did not even bother with a pressure guage; they just had a light on the CWP. I presume they were standard gear pumps like 100,000s of car oil pumps which seem to go on for ever. I can see why EH thought it might never cause a problem.