Have 2002 trailblzer 4wd 133,000 miles. trans shifts from first to second wont shift out of second,mechanic stated had to be rebuilt/ any suggestions or thoughts on this, is trans really shot thanks

 

same thing happened to me one day-- on highway- coming down a hill at about 70...
engine suddenly revved to about 5000...

I slowed down-- and exited--- soon found I only had 1 and 2...
in 2nd I would drive and it would rise to about 3000 and never go into 3rd.

it was the 3rd band/clutch-- something like that.
required those parts to be replaced.
I dont know how much of a tear down was required.