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So I was driving around 60mph on cruise control on a long stretch of road that rolls up and down gently. When suddenly my tranny starting make a really loud whine, so I clutched and costed, just kept whining, then I put it back in 6, took it up to 70 got a little louder and I went back to coasting baffled. Then all the sudden the whining/screeching stopped and I put it back in 6th and cruised on... What the hell could that be? Help please!

Only thing that might be related is for some random reason about 2 weeks ago after a long night of driving, with maybe 2 pulls involved, I parked her backing in on my really steeply sloping drive way, in the morning there was a foot and some change in diameter redish pink stain on the drive way. So I immediately moved into the level garage, and dident leak another drop. Drop it pretty normally for 2 weeks, and then that weird random thing happened this morning.
Thoughts? Ideas?

2006 m6 GTO H/C/B with full tick/monster clutch kit.