Hi Robbie,
having had a 1984 90" in the past and also needed a fuel cap, if your cap is the type like a Series,(large disc about 3" dia) you may find it easier to replace the filler pipe and fit a later type cap as I found the orgional type cap was only available from Landrover and must have been made from a precious metal with a price to match! I could not find any other cap to match the size or fixing lugs.
