Here are the details of the official importer of WP suspension into Australia.
BUTMAC Pty
13-39 Pilbara street, Welshpool WA, 6106
Locked Bag 200 Welshpool WA, 6106
Telephone : (08) 93514763
Fax : (08) 93516694

I haven't been able to find any part numbers for you, so just give them a call. Let me know how you go.

Dean.