Years ago, I read about this diff on Tamiyaclub (Blasphemy!

).
It's mentioned in the second post on page one by the member Tanker (2).
https://www.tamiyaclub.com/forum/index.php?/topic/9140-srb-balldiff/
I wondered about it for years and came to the conclusion that I'd probably never see one, or find out who made it.
As luck would have it, one finally turned up. It's made in Japan by a company that used to be called GO PRO RC, but is now known as Goyo RC.
The diff has no through bolt or thrust bearings. It is indeed pressurised by the alloy SRB gearcase halves using the washers (gold coloured) that sit between the bearings and the diff. Apparently, there weren't many of these made.
Got to find them all.

Chris.
Toys.............they are!