Chosen Solution

I need to replace the rear enclosure of my 2017, 27” iMac. I’m reluctant to pay out for a brand new enclosure and used ones for 2017 are difficult to find (eBay, etc). But- used enclosures for the 2015 model are more common. On close inspection of photos, all the screw posts for the internal components (logic board, etc) appear to be in the same positions for both years. Does anyone know if it is possible to use a 2015 enclosure to fit the internals from a 2017 iMac? I wouldn’t mind making a few compromises if required.

Apple has different P/Ns for the rear case iMac 27" Retina 5K Rear Housing Unit - Leg Version (17) - 923-01666iMac 27" Retina 5K Rear Housing Unit - Leg Version (L15) - 923-00650 There is clearly a difference here, without having the parts in front of me I wouldn’t be able to tell you. How about telling us why you need to replace the rear case (post some pics if that helps). Maybe we can offer another solution.