Hi Phil,
I'm new to Perenties, like you, but have plenty of experience with the humble Land Rover.
I believe what you are after are drive flange caps, the little cap over the centre of the drive flange. The type of caps on the Perentie are shared with every 110, 90, County and Defender on the road. Any LR dealer or parts specialist will have them.
I'm from Sydney, but I know two good places that are Brisbane-ish; M.R. Automotive in Redcliffe and British Offroad in Landsborough.
If you are after any
technical information on your Perentie, I recommend you look at the Isuzu Landy Enthusiasts Section of AULRO (
www.aulro.com)