When I'm in gear and I let off the gas, I can hear a whining type noise. I'm pretty sure it's the transmission. Also at low rpms I can hear it when I switch gears, and when I let if the clutch I can hear a small clunk type noise. It doesn't make the car buck or anything, it just sounds like a drop type noise. Any suggestions? Would changing the tranny fluid help? My car has 67,500 on it.