Gearbox problem

[The Monty]

The last few mornings when I take off and do a quick u-turn, the gearbox has slipped and/or held gear to long, then slammed into gear.

Gearbox was full, and hasnt leaked at all.

Coming home today, the car was vibrating more than usual, with lots of harmonic sounds at certain RPM, accelerating, then decelrating. After 15km of this at 100km/h, the car went dead silent, and drove smoother than Ive ever felt it, gears shifting good and solid, and everything normal.

5km from home, gave the car a little stab, kicked back into third, and the vibrating returned worse than ever to the point where I have had to slow down to about 60km/h.

All of a sudden, everything back to smooth, turned a left handcorner, and it came back again.

So I got home, stopped, and put it straight on ramps. In this time (5 minutes) its left a pool of fluid all over the ground. Its tranny fluid (obviously) and its coming from the output shaft seal again, I only replaced it 10000km ago, and havent been to the drags, but had that world record attempt day.

There is also a peice of circular (perfect circle) that looks like wire/shorn off something metallic/metal o-ring hanging from the out put shaft, about the diameter of the tailshaft.

The vibrations and slipping lately, and the amount of fluid it lost so quickly has me thinking that its something more than just the output shaft seal.

Anyone have any ideas?