The 500 came about in 1960 and was the responsibility of the crawler plant. It was to compete at a price. Since White also purchased Oliver that year and did not include the Cleveland plant it became the responsibility of Charles City Don't forget there was also another david Brown the Oliver 600. Also there are 2 series of the Model 500. One piece of paper I once had was from the David Brown company telling the readers that the sucess that Oliver had with the David Brown was one reason they  came to the states. Remember they were in Ontario before this. I have seen a few of the older David Brown tractors at the Yoder &amp; Frey auction. They came out of Ontario The 500 is the model 850 david Brown. Questions?