You are generally describing what sounds like excessive clearance between the ring and pinion gear. The clunk is usually a dead giveaway. Humming could be a bearing, but most likely it's the ring and pinion clearance. This will need some attention soon.

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Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.