I bought a fiesta mirror and the mirror casing and pivoting mounting arm mounted perfectly to the puma bodywork/metal baseplate.
I had to bin the new plastic fiesta baseplate that came with it as it wasn't identical (body shape obviously different). The mirror casing although it interfaces perfectly to the puma baseplate, it is about 15mm to 1" longer overall so my mirror is slightly further away and sticks out slightly more now!
The electric mirror motor bits are totally different as is the mirror glass mount itself so I would now have to buy fiesta mirror glass if I ever cracked this new one (round attachment mount rather than square).
Not bothered messing with the electric socket yet.... I'm hoping it will work if I just wire up the right bits/buy a fiesta socket half for the car side pushing the mirror to adjust it doesn't seem that difficult to be honest, but I know I'll miss the heater when it gets cold!!