I did a quick search to see what?s out there. The 912A-585 seems to be the one they sell for jeep fronts.
The first ones i saw were clearance 912A398, low preload for jeep front. I am guessing that new number is low preload but with the harder case and 6 case bolts.
The 398s worked great in snow, not great for racing. They are part of the reason for the bad early reputation.
The old high preload number was 912A411. 3 larger case bolts like the 398 suffix diffs.
The new (2007) high preload diff with 6 bolts and harder case is 912A588.
https://www.summitracing.com/parts/dtl-912a588
*edit: it will say ?3.73 up?. Ignore that. The one case size fits all volvo ring gears for 1030 and 1031.
Regarding that early post: I have a collection of several variations on pinions now. I haven?t posted pics, but i can do that with this info too.