Not necessarily. It may need shifter arm bushings at the end of the arms replaced or a good adjustment of the shift rods between the trans and shift box.GM 3 speeds are notoriuos for popping out of gear or locking up over time.That said, I did have to rebuild the shift box on my '50 3100 when the internal spring on the shift dog popped off. Not much to it ,but myself and others did it by trial and error as we never found a factory description of what was needed.
