Thanks you very much for all the info, Y2KMondeoSVT, will follow of your advice.
I was asking about the D79 'cause I sometimes get weird answers at some of the dealerships(!) around here. For example, when I asked about the price of the pollen filter at one place, answer I got was "I've never seen one here" (they've been at this location for at least the last 6 years, selling Mercury's and Lincoln's; then Ford's when the Mercury dealers in canada were converted to Ford's)

. Another dealer's answer was "Don't waste money changing it, unless there's a musty smell in your car when you start the AC".
Again, thanks very much!