Greetings,

I purchased a 1989 Dodge 150 w/ 85k miles, automatic transmission.
Sorry, not sure of transmission or engine make/model.  After driving it
for about 20 minutes, I went from surface streets to highway.  I began
a slow acceleration.  I was able to hear a loud spinning noise with a
slight grinding as the the transmission began to shift.  Next came a
loud clunk and the truck shook as the gears engaged, at least thats
what I think happened.  This occurred with all shifts.  If I stayed at
a given speed there was no issues.  Previous owner states that he never
had this happen, but he hasn't had it over 35/45 mph in a year.  Just
drove it to the store, dump, etc.

The fluid is low, just at the bottom of the line.  My current plan of
action is to replace filter/fluid & tighten the bands.  My question -
is it worth doing this or am I wasting my time and should just replace
the transmission?

Any input is greatly appreciated.  

Thanks,
Chaz