Don’t know what the hell they mean by axle shaft freeplay causing that, that would have to be pretty massive I would think to cause that.
Slip yokes have been a problem on pretty much all F-150s since at least the 11th Gen F150s, could go back further but I don’t know. My 11gen has it bad.
Presents itself usually under coasting then throttle, or from a stop. Audible and physical clunk
As much as I love my ford they just can’t seem to get that right for some reason.
Might not be your issue but that’s my guess