So after looking around, I'm reading that there are only 2 top screw holes for the rear plate on our cars. Is 6mm the correct size, and if so is there a certain length that works best?

 

yea its m6. I think 8mm long?

 

Can you please do me a huge favor and post a picture without your rear plate on? I need to see what it looks like underneath.

 

I can't actually. The stupid thing which holds the nut mount onto the bumper has broken off, so the screw spins in place forever.
I've already tried to get it off before so i could replace the ugly rusty screws, but only way that's gonna happen is if i pull the bumper

 

^^^
Same here!

 

I can affirm it is a 6mm screw, 16mm long, at least for my 2011 G, for the rear plate.

I experienced what some other people did, the rear screws broke when removing. I lucked out. The screw broke off deep enough that I could remove the clip. I soaked the clip with the broken screw in liquid wrench, which did the job to allow me to remove the broken screw.

Since the dealer was closed, I could not replace the little rusty nut clip, which I saw in another thread: “This Nissan part number for the replacement "J" or "U" captivated nut clip (called a spring clip) is 01241-00881”.