Why can't you flip direction on the 336 gearbox?

[Lyngeled]

I have opened a 336 and it looks as if you can. I have read some saying that it is not possible. Conical bearings in both directions on the axle which will be affected by the change in forces.

[jbcollier]

The Renault 3xx series transaxle is very slightly "hypoid".  The axes of the ring and pinion is offset from the true centreline.  It's not much but it's enough so you can't "flip" the ring gear to the other side.  People have tried and confirmed this.