Volvo uses 4 rubber "dampers" in conjunction with bolts and other hardware to mount the shift lever cage to the back of the transmission. When these bushings age they can crack and fall apart. That translates into loose and sloppy shifter feeling.
Note: Earlier models (1978 and prior) use two of a different style bushing in place of these four. If you're unsure if your model has it's original transmission it is not a bad idea to inspect what is currently on your car.