Having the issue on my W123. Shifter feels loose and it only starts in neutral. Have not done anything yet other then look at prices for the parts.
On a W123 the transmission is in a tunnel. There is not much room to deal change the neutral safety switch which means more work to take apart what is needed to lower and or move the trans around so you can get at it.
The shifter bushing are not so difficult to get at so I think it is better to start there first. If fixing them cures the problem I have saved a lot of work.
If the linage bushings are shot I think there is still that lack of room to deal with but have not tried it yet.
On a W123 Gasser
http://www.benzworld.org/forums/w123-e-ce-d-cd-td/1417360-diy-console-shifter-bushing-replacement.html
http://www.pelicanparts.com/techarticles/Mercedes-W123/117-INTERIOR-Shifter_Bushings_Replacement/117-INTERIOR-Shifter_Bushings_Replacement.htm
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