[Leucosticte]

So I've been having an odd clicking that comes from the shifter under braking/deceleration that popped up a few months ago and it seems like it's been getting worse overtime. The shifter doesn't seem to shake or anything, it's just a noise.

First of all it's probably a good idea to mention the new parts relating to the drivetrain that I put on the car, so here they are:

1. New rear driveshaft a couple months ago, to solve a bad U-Joint.
2. New transfer case mount + poly insert, did this over the weekend and the noise seems to have stayed the same/slightly worse. Old mount had tears in it.
3. Replaced the shift lever since it was bent out of shape during my manual swap (oops.)
4. New front driveshaft that I installed during an oil pan gasket job, old one was rusty and binded up at certain spots.
5. New engine mounts that I installed while the subframe was out. (Old ones were a couple mm lower)
6. New Valeo single mass clutch and flywheel 2 years ago during my 6mt swap.

The big diff bushing on my car has small cracks in it, I'm not sure if this could be the reason why, but I doubt it since I'd expect it to matter when I'm loading up the drivetrain.

Does anyone have any idea of where to begin with diagnosing this problem? It seems very odd to me since it's only under deceleration and the timing of it seems totally random - some days it won't occur, some days it does. My theory right now is that the shifter carrier nuts somehow got themselves slightly loose despite the Loctite on them.

I'm curious if any of you have dealt with this and what you did to diagnose/fix the problem because this seems beyond my level to diagnose.