Hello and thank you for using JustAnswer, my name is ***** ***** I will be helping you on your question today.
I understand your iMac display has goine out and you want to know if you can replace the screen itself with the one in the thunderbolt monitor? This cannot be done as they are different connectors on the inside.I suggest you buy the screen yourself here: http://www.ebay.com/itm/Genuine-Apple-iMac-27-LCD-Screen-LM270WQ1-SD-A2-/221116914621and use this guide to replace it: https://www.ifixit.com/Guide/iMac+Intel+27-Inch+EMC+2309+and+2374+Display+Replacement/1632
Let me know if this helps or if you have any other questions and if I didnt understand your question correctly. Thank you.
Oh, I am sorry. Could you explain what you are trying to do, please.
Oh, the Mac thunderbolt monitor is the fault screen and you want to replace it with the 27'' imace?
That would be the same issue, you will not be able to swap the screens out.
Have you check ebay, thats usually my go to for second hand.
What was apple charing you?
Have you looked into your local tech offices? They may be able to just replace the faulty parts of the screen which will be significantly cheaper.
You're welcome. Best of luck to you.