Life magazine have teamed up with Google to put up nearly 2 million images online - http://images.google.com/hosted/life.
I was looking through them and found these great images of the equipment at work on the Mangla Dam project in Pakistan in the 60's - http://images.google.com/images?q=ma...=source%3Alife. They had around 80 of these Euclid SS-40 scrapers on the job, which were equivilant to the Cat 660 scraper. There was also a similar number of Cat 660 tractors pulling bottom dumps along with a massive number of D8's and D9's.
This is great site with lots of images from other notable projects and equipment from the past.