Hope I use the right word for the inner "link" (the one with the steell balls) for the drive shaft to the gear box.
Changed these joints at the left side of the car before the season. Just had a failure at the gearbox after perhaps 8 track days (1000 miles I would guess). I believe that is a short replacement period, they should hold longer.
The joints is not original ones but the supplier a small race oriented company I trust so at first I do not think this is a problem
I have movements of the gearbox suggested as a reasonable cause.
Or it was just what we call a bad "monday sample".
//TL