For the sake of an update for anyone else in this situation, this is what I bought, encountered and resolved.
This is for the front passenger side of my 2012 Limited 3.5 AWD ecoboost. Initially I got an axle from O'Reillys which was the Precision CV shafts FD8331. I realized this did not fit because the splines would not seat at all. I then ordered the motorcraft TX833 from carparts.com and this ended up being the same inner diameter/spline count as the O'Reillys one. I came up with the idea to take the inner CV joint cup off the axle that was taken off the car and swap it onto the motorcraft TX833. The inner cv is not the same on the FD8331 and the boot would have not worked. I cleaned out all the grease out of the old inner cv and put it on the new axle, replaced the metal band and installed. Drove around the neighborhood and have no issues. Hope this helps someone else.
This is for the front passenger side of my 2012 Limited 3.5 AWD ecoboost. Initially I got an axle from O'Reillys which was the Precision CV shafts FD8331. I realized this did not fit because the splines would not seat at all. I then ordered the motorcraft TX833 from carparts.com and this ended up being the same inner diameter/spline count as the O'Reillys one. I came up with the idea to take the inner CV joint cup off the axle that was taken off the car and swap it onto the motorcraft TX833. The inner cv is not the same on the FD8331 and the boot would have not worked. I cleaned out all the grease out of the old inner cv and put it on the new axle, replaced the metal band and installed. Drove around the neighborhood and have no issues. Hope this helps someone else.