1984 cutlass supreme

Usually that means it’s time for a transmission overhaul.

Answer not posting

If the car will move in reverse but won’t go forward, the likely cause is worn out solenoids, clutches, or gears. Check the transmission fluid, as a low level is a potential reason for making the car move in reverse only.

The transmissions in this era are too small for the vehicle and most failed decades ago. I'd suggest replacing the transmission with the better THM350 if it'll bolt up. Hope that helps! Jim