I'm on my second cap, which came with my second shift knob when the first one lost its grip on the stick and hung by the OD switch wires. That made driving interesting.

It wasn't long before that cap started rattling, but as weird as it sounds, I like the rattle. If it bothers me, I crank up my 10-watt factory radio.

On two different occasions, a well-intended mechanic at my dealer placed some black goop under the cap to stop the rattle. Over the next few years that goop slowly oozed out onto my hand until there was none left, upon which time the rattle returned.
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Mike F - 1984 244 DL - 231,000 miles - with Euro headlights and lots of gauges