ok... since i know something about this
the faulty part which demanded all GT's be grounded until fixed is both rear bottom control arms are cast aluminum which ended up not being up to prototype spec, and prone to fracture (likely due to temperature cooling faults) ford has replaced the part with an above prototype spec bilit aluminum controler arm.
in order to replace them, they arent taken to dealers shops... as it wont fit on a hydrolic lift, but special wooden blocks are placed underneath the car, and a team is going around the country to replace the defective parts.
while doing this, they are also using a 'speedy sleeve' to fix a main bearing oil leak that is on some of the cars... that is caused by uneven metal to metal contact. a several hour job, but quite cheap when compared to using a bilit aluminum vs. cast aluminum.
i dont believe any cars delivered after mid november had either fault