I have a 98 blazer 4x with about 160,000kms. Automatic Trans. At highway speeds trans fluid is pushed up the dipstick tube and drips off on to the exhaust manifold. Any Idea's. Thanks

 

Sounds overfull when hot. You may be foaming the fluid which could be an indication of being overfull or fluid that is in of changing or both.

 

It is not over full to start but will keep pushing fluid up the tube untill it starts to slip, I'll add 2 or 3 litres to bring it back in the crosshatch and it will be fine, unless I'm on the highway where it will just pump it back out again.