If you can find a dealer with one on hand the p/n for the hard drive is 001-074-480. It appears they have recently become no longer available in the USA so hopefully you can find something in the supply channels. If you don't find anything, it is pricey but there is a Solid State drive option (pn 001-495-260-00) that could be special ordered but you would need to check with the Furuno dealer on price and availability.