One of the books I have lusted over for a while now is called Porsche 917: Archiv 1968-1974 It contains tons of info on all of the 917's, as well as lots of engineering
porn diagrams. It's been super expensive ($1,300 for a new one as of this post!) and it's in German, but the porn diagrams aren't and that's all that really matters.
But now the publisher is coming out with a new version and it's much cheaper and in English (ya know, for the articles). And all for a shade under $60.
I figured I'd let y'all know as this book was talked about here a little a while back