I recently bought a '73 240Z with an L28 and 5 speed swap. The transmission operates perfectly, but it makes a "whirring" sound when moving and when the clutch is out. When the clutch is depressed, the noise stops. From what I read, it seems it has a bad input shaft bearing. Also, I was going through and changing all of the fluids and found what I would call "significant" shavings and a few large chunks on the magnetic drain plug. The large chunks look to be pieces of bearing race. Can anyone smarter than myself on transmissions confirm this diagnosis? Also, being that the transmission works well, how long can I expect to drive it before something bad happens? When something bad happens, is it going to make things worse and totally grenade creating more carnage? Any insight would be helpful. Thanks!