I have this deceleation noise that sounds like a grinding from the front of the car,some days you can alomost feel it through the floor. It is more noticable going down a hill at 2100 rpms foot off gas 4th or 5th gear.As soon you touch the gas the noise stops.A mechanic said it could be the Input Shaft Bearing.What is an input shaft bearing and problem that should addressed quickly? It's been going on for long time.I had it into the dealers three times,the last changed changed to Redline fluid and this did not help.Any Ideas if the input bearing could be the problem or maybe another problem?