Mine is the same as the one above, thank you Claude for the photos.

I spoke to NGK head office in Australia and they were able to give me some possible alternatives, OZA23-D2 (Ford Falcon) or OZA2F-2B (Holden Commodore) depending on thread size.
He also said that the Titania ones are more resistant to unleaded fuel, so on next days off I'll compare them.

Cheers,

Mark.

I found some more info on oxygen sensors here:

http://members.pcug.org.au/~jdeakins/facts.html

It relates primarily to Nissans although at the bottom of the page it has usefull information on naming conventions etc.