Seamaster GMT 'Great White' Caseback Compatibility

Does anyone know if the casebacks from the Seamaster 300 (pre-2018) with the 1109 or 1120 movement fits the Seamaster GMT 'Great White'? Same question for the Seamaster GMT 50th.

I remember reading an article by @Archer (https://omegaforums.net/threads/great-white-bezel-on-a-50th-anniversary-gmt-disappointment.63155/) that there were dial and even case differences between the 300, GMT 50th, and GMT Great White, but I wasn't sure if those extended to the caseback as well. I am primarily interested in putting a sapphire caseback from either CWC (https://www.customwatchconcepts.com/product_info.php?products_id=115&language=en) or Sprialwinder (https://www.spiralwinderwatchparts.com/product-page/sapphire-exhibition-caseback-for-seamaster-300m) but couldn't find any threads where people have tried, or part numbers for the original 300 and GMT casebacks.

Wouldn't CWC or Spiralwinder be the first stop in finding this out? They might say they don't know, which prompts the question here, but they might say no, which is your answer.

Absolutely, and I did indeed contact both of them. I had not heard back though, and thought that this forum might be another good reference since some members either have both models, have access to the part numbers for both, or have serviced both.