i've got two copies of 'project cancelled'. the first, is a first edition, i think, it has a metallic silver cover, with a line drawing of what looks like a SO vautour on it. the publisher is bobbs-merrill. it doesn't have the chapters on the jumping jeep or the helicranes.
the other one is a second edition, the cover has colour illustrations taken from a TSR.2 brochure, and it _does_ have the jumping jeep and helicrane chapters.
i've also seen the third edition, this has a monochrome cover, with a picture of the P.1121 mockup on it. i didn't get it because the content appeared unchanged from the TSR.2 cover edition.
i can't give you any more information at the moment, as my library is still in store following my recent move. hope this helps,
cheers,
Robin.