Some Collectors are trying to get one of every model in a range from a particular manufacturer. for example Ford 1000 series tractors, with a Ford 2000, 4000, 5000, 6000, 7000, 8000 & 9000 model. Or the Massey Ferguson 100 series, comprising a MF 130, MF 135, MF 165, and MF 175. Others aspire to collect every variation of one model.