After checking out the diff oils at supercheap on-line, I found this listed, and purchased it. I'm hoping it's still available, as it's not listed in the Penrite web-site search. Supercheap says it's a special order from Penrite, so not kept in stores, and will be delivered.

Penrite HD Gear Oil Premium Mineral Non Limited Slip - 80W-90, 20l. ( only available in 20 & 105 lt drums and has no "slip" additives ) $160 for 20lts.

We'll see what happens.