Gearshift Rattling?

On our old UniMoG transmission, the gearshift rattled terribly, it nearly drove you nuts on the highway.  Our solution at the time was a bungee cord hooked to the gearshift & the passenger seat.  It didn't put much force on the gearshift, just enough to keep it from vibrating.  The bungee could be removed easily when using the lower gears exclusively, so that it didn't piss off the driver to have a tethered gearshift.

While replacing our transmission, we discovered that there was supposed to be an o-ring in a groove on the gearshift.  Looking closely at the old one, sure enough, there was a well squished o-ring, much too flat to do the job.  The o-ring on the new transmission was actually a little big & torn while being put into place, but it did keep the gearshift from rattling for quite some time.

While fishing through our drawer of leftover Volkswagen gaskets (doesn't everyone have a billion leftover gaskets for their type I engine? Every time you want valve cover gaskets, you buy the whole gasket set because it is cheap) we came across an o-ring just the right size!  If you want to get picky, it is a D-ring, with the flat part of the D facing toward the center of the circle, but it fits the gearshift perfectly.  It is the sealing ring for the distributor, not something you need all that many of, they don't get replaced often.  Now we can keep our gearshift from rattling & carry a spare o-ring without spending any extra money.