I have a 1991 740 turbo with 195,000 miles on the clock. In the last few months it has developed two problems with the transmission. The first is that the clutch pedal will drop to the floor. All I need to do is pump it once or twice and it comes right back up. The second is during hard acceleration in first and second gear. The rear end develops a stutter, as though all of the power from the engine is not getting to the rear wheels. The engine revs smoothly up to redline and there seems to be no slippage in the clutch, it very easily will spin the tires. I recently had the fluid in the differential changed, and was told that I did have a leak at the pinion gasket, but my mechanic did not have the tools to change the seal. Is my rear end going as well as my clutch?