This thing drove me nuts towards the end of last winter. The weather warmed up and it went away. No that the weather is cooling off in the mornings, the car has a clunk when I push the clutch in on my way from 1st to 2nd. It also does it when going over some bumps on the driver's side rear. Could it be the differential mount bushing? I had the bushings that under the rear seats replaced already. But that is almost where it sounds like it is coming from. Any ideas about how to further diagnose?