Since the previous post I found the Australian agents for WIX filters, Engine Australia, and low and behold they have some 51001 filters in stock and at just $10.60 each so I got a couple. Even with domestic air freight from Brisbane they were cheaper than the Fleetguard 510 I had bought locally.
Even though they are listed for 60's GMC trucks, Clark lift, and Graymarine applications I am 99.9% certain it is the right one for this particular oil filter cannister as it is identical diameter and height as my NOS sample on the left in the picture. It is a bypass type filter too.
There is a slight difference in the bottom hole diameter: 0.552" and the top hole diameter: 0.480" and when I had a good look inside the cannister there is a thin collar at the bottom which would account for the two different size holes.
It fits like a glove so between the three new ones I have a few years supply of this consummable.
They can be contacted at:
sales@engineaustralia.com.au
Mark Bryers, who I dealt with, was very helpful and said he was also ordering in some 51006 elements which are listed for the Ford sidevalve V8's. They are shorter like the Fleetguard 510's and are a closer fit in the cannister. I believe the later 8BA Ford engines used a more squat cannister than the earlier wartime engines so these may refer to them. They will be coming in in January. Same price as the 51001's.
Hope this is of good use to fellow Australian CMP truck restorers.
Cheers,