Just being too lazy to look it up, and it's been too many years to remember
exactly, but what's the deal with the pin that holds the cup onto the rear
end of the shift rod?

I do recall that the setup is almost identical to later manual transmission
vanagons.

When I did my engine swap a month or so ago, I noticed that pin protruding
and had been noticing slightly sloppier shifting. While under the car I
tapped it back in. When I look at it yesterday it was sticking out almost
enough to fall out.

I drove it back in, followed it with a few taps of a punch to recess it,
and then lightly peened the hole in the cast aluminum housing.

This is a problem I don't need to happen on the road. I am pretty sure it's
not a split pin, but it is tapered? Is there anything in particular I
should be doing to make sure it doesn't fall out, but comes out if I want
it to?

Jim