We bought our first 510 in 1964.  Traded in a Massey 90 special.  Full price of the 510 was $12,594.35.  Dealer allowed us $3,462.95.  Overall it was a decent combine.  But we spent a considerable amount of money each year keeping it going.  We always had cutters take part of our crop of back in those days so most of the time we never used much beyond a week or two worth of cutting.  Reason I am saying all of this is because our cousins farm right next to us and they bought a new JD 105 a few years after we bought our 510.  They used only that combine to take their entire crop off which was over 1,000 acres about the same as us.  And that thing ran year after year after year.  And they didn't spend near the amount of maintenance and money to keep it going.  It was finally retired in the late 90s.  My opinion of them even though the 510 was fancier and more stylish they cost more to run over the long haul with all the work it took to keep them going.  BTW, we still have a 510.  1977 model with a diesel that our neighbor gave us.