Does anyone know for sure (no guesses or 'maybes', please) when the Case-IH Maxxum 5100 Series tractors went on sale in the US - reference to a back issue of a farming mag or some other evidence would be welcome - and likewise the 5200 Series upgraded models. Info would be very helpful for an article I'm writing for 'Classic Tractor' magazine (covering mainly '70s-'80s tractors) here in UK.