Mercury is getting a version of the Ford Freestyle, which is based on the Ford Five Hundred/Mercury Montego sedan platform.

I'm pretty sure if Mazda uses Ford-derived V6 engines for this upcoming model, they will be off-the-shelf Duratec units. For example, the Mazda 6s has a Ford Duratec 3.0 liter block but with Mazda heads which include a cam-phasing type variable valve timing system. If Ford is working on a 3.5 liter Duratec my guess is Mazda will employ a similar head design to differentiate its version of the motor from Ford.