The car (1991 Lexus ES250) would not go into gear, so we pushed it and
it started moving forward... while driving the gears slipped again.  
Put in transmission fluid and made it home.  The problem now is that
when in reverse you hear a grinding noise and the car hesitates before
moving.  Vehicle works fine in drive.

Any ideas on what the problem could be... best and worst case?  Any
and all help would be appreciated.

Thanks  :(  :?: