For the last few months, I've been updating the wikipedia article for Dudley. A lot of this information, not to brag, was provided by yours truly.
http://en.wikipedia.org/wiki/The_Adventures_of_Dudley_the_Dragon
There probably aren't many Dudley fans on here, but if anybody is able to dig up any additional info, feel free to add it (as long as it's legit; I'm still trying to confirm the accuracy of the VHS releases somebody added a few weeks back).
Also, very recently (about a minute ago, to be exact), I found information on an actor named Anthony Scavone. According to the IMDB, he was Dudley in the American brodcasts. Though it's not specified if he was Dudley's voice, I'm guessing that's what they're implying.
My memories of Dudley airing on PBS are extremely vague, so I really don't remember what American Dudley sounded like. Up until now, I always assumed that Alex Galatis' voice remained in the American airings. I actually can't imagine somone other than Galatis doing Dudley's voice. If anybody has any old PBS airings, I'd love to see them.