[jandroid67]

If I bought a used phone- even it it was an ATT/ T-Mobile... could I successfully transfer my motherboard and other critical components onto it and have a working phone?

My phones LCD /digitizer is broken- I just need to get an image on this old phone so I can wipe it clean before recycling it... thanks...

[GSDer]

A hammer would be a much cheaper alternative to buying a used phone which you would then have to swap your parts into.
But you should be able to swap the guts of any variant into the screen/framework of another.