I got this T440P for free, but it needs some work.
this post had a lot of info that was helpful when choosing parts:
https://octoperf.com/blog/2018/11/07/thinkpad-t440p-buyers-guide/
these videos were handy for installing the trackpad without dealing with the official lenovo way, and getting the drivers to work:
https://youtu.be/vOXz-tr41KM
https://youtu.be/iap3qJKpR84