Dome light cover

Got one from my 72 Demon but as old dome light covers go, it's yellow now. I'm probably buying a new one. What's so special about a OEM cover? Don't see any part numbers on mine unless it's an old aftermarket.
lol... It's not a big deal at all.. Halfway joking because I've posted a bunch of legit stuff I need and just threw this out there.. I'm going to buy a new one.. Thanks for responding though... I guess I need to take this post down..