I need some opinions on what may be wrong with my car?

I have a 2000 Ford Focus ZX3. Anytime I let off of the acceleration, there's sort of a rumbling/growling/humming type of noise. I've had a few people tell me that it might be the cv joints, but from what I've read those are more likely to make clicking sounds, and I haven't encountered that at all. I'm just not sure what the deal is and I'd really appreciate some opinions.

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