[KyleGoetz]

Well, I wouldn't say づ is pronounced the same as ず in standard Tokyo dialect. For example, if you pronounced 続く as つずく, I think people would say you're mispronouncing it.

The "d" sound is there in つづく to the best of my knowledge. That's what I hear, anyways. Tsudzuku. Not Tsuzuku. But maybe it's like the difference between the various が pronunciations depending on where it appears in a sentence. The が in 学校 is technically pronounced differently than the が in 背が高い. It separates commoner Japanese from newscaster Japanese.

My Japanese professor in college couldn't even make the distinction, but I could! I remember asking her one time, and she told me she couldn't even make the newscaster が sound. It's like the "ng" in "sing" + "a."