Go with a known quality name brand. Non greasable i.e. permanent lubed joints are considered strongest verses greasable if all other things same. The grease passages can weaken the cross piece.
Full circle snap rings are preferred to the stock C rings. You can buy these. However stock axle forks will need bit of grinding to clear the full circle snap ring, easy job. Way it is, the stock with fork not cleared all around, they had to use the C ring, but that C ring can walk around, and it can walk right out of its groove as it walks up the metal that will be ground away to fit a full circle full circle snap ring.
Spicer is a good brand of U joint. it was recommended to me by 4wd people as a good brand, I run it, and have done rock crawling with 33x12.5 tires, U joints have not failed me.
Sure you may find a half price copy, or no name joint, but if it fails, its a lot of work to replace, and failure can destroy an axle, negating any savings of low purchase price of the imitation U joint. Don't go cheapo here!
Locally, I dont know what are good brands available to you, so ask a local 4wd shop, or 4wd club.
My friend lost a cup on his axle U joint when the C ring walked out. The axle fork got bent when this happened. So he had to replace the axle, he clearanced his axles with a small grinder and fit full circle snap rings on both left and right axles, That never will strand him again.
So consider...
a.. Use non greasable joint.
b. Use name brand for sure.
c. Use full circle snap rings.
Cheers from America! Australia is a real nice place, nice people. Been there, so I say that with certainty.
Are there a lot of XJs down under? Do you drive a US built xj or other? Right hand drive, correct? What is the xj scene like? I know Toyotas where big in Australia a long time ago, saw a gazillion of them. There was an industry of converting American cars, to right drive, big market for importing muscle cars and classics, but unless they are a museum piece, they where converted. I saw dashboard assemblies, for Mustang, Camero, Malibu, etc... even pick up trucks like Ford or GM. These dash assembly's were made with right hand drive offered for sale as conversion kits, so after conversion it looked like it was factory made right drive. Seemed to be a good sized right drive conversion industry for the car hobby market.