Chevrolet: Transmissions, transmission leaks, chevy astro

Question
1993 Chevy Astro EXT - 200,000 Miles.

The transmission slips in first gear when the vehicle has run at highway speeds for approximately 45 minutes to an hour. It only does this once in a while so this seems to be an intermittent problem. The transmission fluid is a little brown. Overall the transmission shifts well in each gear. There were a couple of transmission leaks from two lines in the front near the trans cooler which were tightened by a mechanic. The transmission sounds louder since then and seems to whine when the vehicle first starts to move. Any Ideas?

Answer
Well the transmission fluid should be changed every 60,000 miles.

It should be bright pink. Brown means its long overdue for a change.

You can try flushing it from a tranny shop. Otherwise it could be on its way out. Its impossible to diagnose until you actually open up the tranny.