My TL VR AWD has a lot of play when in gear, and it sort of annoys me.
I'm wondering what needs to be replaced and how far into the gearbox I need to go to replace it to get rid of the wobble

Cheers.

I would suggest it's more likely to be a broken engine or gearbox mount, rather than the box or shifter itself.

It's not due to acceleration or anything, it just feels like something from the inhibitor switch up has let go or worn away

To state the obvious, have you exposed the shift linkage at the stick to have a look at where the play is?

What do you mean by play. As in the auto shifter knob moves around?

If you mean the stick itself its nothing to do with the gearbox. Its probebly your shifter assembly worn down.

OP says "feels like", so I assume he hasn't actually dived into the shifter system to see where the problem is. Visual inspection is a must.