2017 Impala trunk leak, what plug is this?

Update:

Plugged that hole up, but still getting wet.
Next I will replace the tail light gaskets.
The part# above I think are not for the newer models.
The 2017 Impala seems to be these part#:
left 84527173
right 84527174

Jim,


Hello all,

I noticed some water in the trunk of my 2017 Impala.
Pulled back the covers and no obvious signs at the tail lights,
I think they fixed the tail light gasket problem by 2017...
Looking around I found an oval hole on the outside of the trunk
lid gasket, see photo below. That hole goes right into the trunk,
right above some computer module. I seen the same size hole
on the side behind the tail light. I can't seem to find the number
on this part to replace it, can someone tell me this part#?
I found part# 15259076 but from the photos this don't look right.
I need an oval plug. Anyone know what the correct plug is?

Thanks for any help,
Jim

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Update #2:

Replaced the tail light gaskets. The bolts seemed lose and it did look like the gaskets was leaking.
But, still leaking into the trunk...
So, I closed myself in the trunk with a flashlight and had my wife spray with a hose.
The seam that runs below the left tail light was leaking a little in 2 places.
Now in the Car Fax when I bought the car it did list rear end accident.
So, maybe even though it looks ok on the outside, maybe the seam seal got opened up.

I got to take the bumper cover off and seal this seam.
What is the correct thing to use to seal these seams?
Will a good silicon work good for this?

Thanks,
Jim