So I found these:
https://eagleonlineshop.com/eaglesho...px?id=DP01-39T
My ability to translate Japanese is limited to Google and it's a little ambiguous as to whether it will work with the ball diff. Looks like it should though and they're not too expensive.
Apparently this problem has affected the touring car crowd for quite some time so I'm not expecting it to change quickly.
I still need a new kit if I want new belts!