Hack job floor shifter conversion rattles and sticks

[Praxiss454]

Hi all,
Took my truck out for a drive today, and as I was at a red light, the gear shifter seemed to pop out w/o actually popping the truck into neutral. So I was unable to shift into a different gear right away. I ended up getting it to work again by attempting to start in whatever gear it was in (2nd I think), and then it let me shift back down to 1st. This isn't the first time this has happened to me.

My truck used to be 3-on-the-tree manual trans, and at some point a PO hacked a hole in the floor and converted it to a 3 speed floor shift. I have a few questions about this setup, hopefully someone here with more experience can answer.

1. What the hell did they do to my truck? (what is this shifter?)
2. Why does it kind of get caught up and unable to shift sometimes? (and how do I fix it)
3. Why does it rattle so much at cruising speed? I basically have to keep one hand on it. There seems to be a lot of slop. How do I fix this?

Here are a couple of pics. Thanks