I'll be taking Pony in to the mechanic tomorrow. It has suddenly began shuddering and then vibrating on the 5-6 shift and at speed when not shifting at all but simply decelerating from 2K rpm. The 5-6 shift shudder has never been present, neither has any 2K vibe and shudder; it's always only vibrated from 3K rpm and without any noticeable shudder. An occasional high-pitched screeeee of a noise also arises intermittently at freeway speeds, and it always sounds like it's coming from my passenger mirror. I can't help but wonder if it's some kind of bizarre sound transference? So...I'm thinking the flex plate might be done for? The car has around 90K miles. Maybe the driveshaft is out of balance and is starting to fail? Who knows? I'm not taking any chances. No sense having a pretty Pony if she can't gallop as a gimp. Will follow-up once the issue is resolved.