I am strongly believing that the seals are letting go on the OD due to high pressure being built up and the breather not being big enough to help with relieving the pressure, the next weakest link would be the seals. I was thoroughly checking out the transaxle after the NORRA 500 and even noticed a little bit of fluid starting to seep from the Secondary CVT input shaft seal, which lead me to believe the stated above even more so.Not sure if they do...There may have been a bad batch of them...or guys were running wide open for a period of time causing pressure to build in the rear diff. Or the bearing on the ring gear is not tight.
I thought my passenger side was going...turned out to be cv grease being forced out through the center slide pin when it got extremely hot. Blew around the diff housing. It was black and thicker than the reddish rear end synthetic fluid.