googling your element number FG2398/2 suggests a crossover to NSN 2940998812191 which lead to several listings for filter elements. One on ebay
https://www.ebay.co.uk/itm/BRITISH-F...-/202204661217 has photo. The photo shows FG2398/203 on the element, I don't know enough about the relevant numbering system to know if this represents a minor variant or a completely different filter. I suggest more research.....