If the shifting on your M56 manual transmission has gotten sloppy you likely need the shift cable bushings at the transmission linkage replaced. If you can not find the OEM rubber bushings, these bearings are a great substitute. You can get 2 to do the job. A couple of washers as spacers will also help.
These will probably work on other Volvo transmission cable linkages like the automatic transmission and the M58, M59, M46, and other vehicles like the 960, 940, 740, 240, etc.