If all else fails Theo ..... I went down this path last December & ended up settling for non original, but an acceptable working alternative for next to nothing really.
Here's the thread with some interesting info & ideas from others here -
http://forum.fefcholden.club/index.php?topic=23624.0The units I bought were US imports from an Aus supplier. They did take a few weeks but that was fine for me.
Cost was $10/pr + $4 post.
Website:
http://www.classicpickupsupplies.com.auE-mail:
classicpickupsupplies@yahoo.com.auPhone: (07) 5446 2667.