nasty shifter play

I was given a 1971 F250 in exchange for some work on a '68 Charger. The 360 smoked, so Sunday I pulled it and installed a 390 4v from my collection.

Here's the problem...the shifter handle "rotates" in the shift ball. I'm pretty sure it's not supposed to, but I can't figure out how it comes apart.

It is a T18 toploader with low 1st. The shifter pivot ball rests in a cad plated steel housing that appears to have "flats" on it so that it can be turned and unscrewed. I tried to turn it, but was being gentle since I really have no idea how it comes apart.

HELP!!!

Streets has the right answer. Sounds like the retaining pin broke. Once you get the handle off, you'll see it.

I took it apart and the shifter pin was in three pieces. A Craftsman 1/4" extension gave it's life to fix it. I have enough extension left to replace it four more times, too!