Hello!
 I purchased my first tractor last summer- an Oliver 500 Diesel, with a loader. Apparently, I decided to start with an impossible-to-find machine. I know it is actually a David Brown 850, imported as Oliver in 1960-1962.  There were only about 750 Diesels sold. It runs and drives (at least until it ate the water pump), but the hydraulics don't work. (the filter was a solid clog). Any info about this little bugger would be helpful, as there isn't much on the Net. I'm looking forward to replacing some rusty tin, repainting, and using it. Thanks!