Of the brands of tractors you list, I would favor the Olivers. I think they are built heavier than the Fords. Parts are fairly easy to get. However, I think you might have a hard time finding one in good shape with a loader. You might want to try the Jimna tractors from China, they are over your price limit, and are bare-bones units, but their small units are very reasonably priced and seem capable. They are sold under a variety of names including Farm Pro, NorTrack, Jimna and Homier, plus a few others. I'd prefer to go with a new tractor over a 40 to 50 year old unit any day, and I'd prefer to go with something that has more features than a Jimna, but with the budget you are looking at, you might be able to push a bit more and get new with a warrenty? You could also look at the grey market tractors, try Sweet Equipment or Corriher's, both are big movers of the grey market machines and have been around for a while. Grey market units are similar to the Jimnas, only used and lower priced. There are advantages to them over the old Fords/Olivers (though I hate to admit that). And the prices are LOW.