Please indulge me for a bit, while I do a bit of counting:
The dissertation was about 70k words. I excised one of three sections from that to save for a later project, leaving me with about 50K words to work from.
Given that I completely rewrote the introduction from scratch, we're actually talking about 45K words that formed the basis for this project, when I began rewriting in earnest in Fall 2008, five years after I defended the project.
Since then, I've seriously revised much of that baseline, plus written another 50K words, few of which I could've written in 2003. I don't know what this says about the pressure to publish a dissertation as a book, but I can say that I needed those 5 years to rethink the central claims of the project, to let the ideas simmer, to teach them a few times and test them against skeptical undergraduate and graduate students, and to generally get comfortable with them.
After cleaning up the notes and doing a complete bibliography, the project with all of it is just under 100k words, and ends on page 316. When I defended, and my family felt impressed that I had written a book, a demurred. This, though, feels like a book. I started writing it as a dissertation 9 years ago, defended it 7 years ago, and barring a few more revisions, feel good about sending it out to a press only just now.