Philia_Bear;105871 wroteThe xr5 box and p1/p2 m66 fwd box are identical in every way
Almost.
Mondeo XR5 M66 is as per Volvo M66, while Focus XR5 M66 has a shorter ratio gear set.
Externally, they're identical and are certainly interchangeable though.
Philia_Bear;105871 wrote
The m56 is the much easier swap in a p80 chasis
Without a doubt, though I do have a spare Focus XR5 M66 box here that I'd love to swap into a P80.