Interesting.....however, a few things he stated are incorrect. The S62 and M62 engines (M5 and 540i respectively) have the same Alusil block but that is where the similarities end. The only M62 carry over are the intake valves. Everything else in the engine as well as the clutch, transmission, and rear end are beefed up over the stock 540i running gear to handle the S62 HP and torque. As for the clunks he was hearing, it could be the universal joints occassionally acting up if he was shifting at low engine speeds without enough RPMs. I often consult Bimmer Magazine to get the real unadulterated info and they know of no wide scale secret problems with M5 clutches, rear ends, transmissions or the like. I have found them to be the most informed, accurate, and unbiased source of BMW info available. A good deal of these problems could be due to driver inexperience with high torque manual transmission cars.