I came across this auction for a PB 180 recently. It has a cutout for the power button and modem on its rear. Did Apple produce some late models with these or is it likely to be a user modification?
That’s a 3rd-party part. I’ve seen those before although I don’t remember what they were called. “PowerDoor” rings a bell in my head but I can’t find anything online about it. I saw it in some YouTube video.
Edit: Found it, and it is called the PowerDoor!
Skip to around 4:50 in. I’ll bet that the owner of that 180 just used some magic eraser or similar to get rid of the branding.
If I remember right, there was also IO covers like this that, in addition to the cutouts, also had a push button latch, instead of relying on a flexible plastic hook to keep the door closed.