Chosen Solution

I cracked my iMac 2017 screen and im looking for a replacement part, but I don’t wanna commit to buying a screen from a earlier model if it won’t fit?

The cover glass is fused with the LCD panel so you can’t replace it alone. As far as using a older display thats not possible either. You have a 5K display and you’ll need to replace it with a 5K unit thats designed for your system. The 2015 model won’t work in your system as the cable connections are different. Here’s one source - BookYard UK: iMac 27" Retina 5K LCD Panel & Front Glass Assembly (new) - Apple P/N 661-07323iMac 27" Retina 5K LCD Panel & Front Glass Assembly (used) - Apple P/N 661-07323