When you go to an Oliver tractor show, you see several different brand names and colors: You'll see old, dark-green Hart-Parr tractors; that's the company that eventually became Oliver. There are yellow Cletrac dozers and tractors, manufactured by Cleveland Tractor company, which was eventually bought out by Oliver.
There's a red Canadian Oliver that for some reason wasn't called Oliver at all. It's name makes me want to laugh, for some reason: Cockshutt.
The Oliver company merged with White in the mid-1970's, and soon there were no more tractors with the Oliver name on them. I've made up a slide-show of various tractors that fly under the Oliver name.