What is the definitive answer to a shifter rattle in 3rd of 4th gear?

I recently had the shift selector replaced, but it was rattling before this
repair so I can't really point to that.  If I apply gentle pressure to the
sides of the stick shift, the rattle goes away.

I'm about to go on a 1,200 mile road trip (round trip) and am concerned
about the severity of this problem.  Though I've been living with it for a
year now.

It is really frustrating to read the archives sometimes.  It is now 4:30
a.m. here in California and I've been searching the archives for over an
hour now.  I will find a post about my current issue and follow the thread,
but it usually leads to more questions, but no answers. Perhaps the answer
is given off list?

Love and Rockets,
DaBomb