Awesome guide thank you.
My late 2013 15” MacBook Pro upper case also had what looked like plastic clips (or spacers of some kind) located in the gaps within the aluminium divider/wall between the battery and keyboard compartments. The teardown above shows the gaps but not the plastic spacers.
They were secured using 2x 000 Philips screws per clip, easy to remove and transport over to the new upper case.
They ‘re not a butt-fit once tightened either, they sit loosely in the gaps - I noticed this in the factory installed upper case before removing.
I have images if there’s a way to upload them?