Got my hands an a T440p with clunkpad and -more important- FHD IPS.PLEASE NOTE:
BEFORE YOU PUT IN THE NEW TOUCHPAD, INSTALL SOME EXTRA BUMPERS/RUBBERS ALONG THE TOP OF THE LID, LEFT AND RIGHT OF THE WEBCAM.
THESE SHOULD BE ABOUT TWICE AS THICK/HIGH AS THE SMALL BUMPERS THAT ARE THERE ALREADY.
PLACE THEM IMMEDIATELY LEFT AND RIGHT OF THE EXISTING BUMPERS.
FAILURE TO DO SO WILL RESULT IN SCRATCH MARKS ON THE SCREEN FROM THE NEW BUTTONS!
That clunkpad needs to go, I want the Trackpoint buttons!
Here are some pictures of the back of a T450/T550 Synaptics and Alps Touchpad + 3 buttons.
Comparing Synaptics (left) vs. Alps (right):
Notice the dotted (Syn) vs. the smooth (Alps) backplate.
Here's a link to more and larger of these pictures: https://imgur.com/a/z5TgiBI
In the larger pictures, please note the differences in the red/blue key insides!
I hope this will help you getting the right one for YOU.
BTW, looking at the touchpad/buttons themselves, I see no noticeable difference between Synaptics and Alps.
If you (for whatever reason) get an Alps, do not despair.
If you don't use the Touchpad and just want those 3 buttons for use with the Trackpoint, the Alps is more than good enough.
FYI: I described the ALPS install further down.
See similar instructions to replace the Clunkpad driver on the X240/s