It looks like the front track width isn't the same.
And I know the brackets that hold the PS pump onto the waterpump & head are not the same. Although the T-Bird brackets may(?) fit in a full-sized car, but not the other way.
The T-Bird idler arm for PS and its mounting bracket to the frame are not the same as the manual versions, I suspect the pitman arm is different as well. Those parts in a full-sized '55 Ford likely have a similar difference (PS vs. non-PS).
These two links say the '55 & '56 T-Bird front tread width is 56 inches ('57 Bird is the same)
http://automotivemileposts.com/tbird/prod1955tbird.html
http://automotivemileposts.com/tbird/prod1956tbird.html
This link for a '55 Fairlane shows the front track width is 58 inches.
https://www.conceptcarz.com/s2073/ford-fairlane.aspx
.