Well, I have the game on X-Box, but it's probably pretty much the same. It took me a while, but I finally figured it out. First off, after you ditch the first dozer, cut to the train tracks between the wood fence. They lead out of town, straight to the coal mine and the second dozer. More of a straight shot and no cops to deal with. Here's the tricky part. I could never get to the third one in time, until I discovered a shortcut. There's a back way into the farm where the third dozer is stashed. I discovered it while on free roam. If you go to the farm on free roam, there's a jump that takes you through a covered bridge then on over to a ridge. Pay attention to this ridge, because you can actually go back the other way. If you see Rosco, you've gone too far. It's hard at first, because you have to get up enough speed to go up the rock wall, but I did it, and had about 40 seconds to play with to get to the third bull-dozer and ditch it in the creek bed. Hope this helps...