Let me make this simple.
Use either a (former) Mercon product such as all the DEX/Merc, D3/M, etc products that exist on the market today. Or, use a Mercon V product. Your steering rack will not know the difference.
How would I know?
Because I worked at the Ford/Visteon plant in Indy, from 1990 to 2006, that manufactured all the steering system components. In fact, for a while, I actually supervised the very EN/FN assembly line that manufactured that steering rack system for your car. To this day, all the steering system compontents are still tested with the equivilant of Mercon, even though it's not licensed to the general public. When Ford switched over publically, our massive multi-thousand gallon test systems were never changed over.
Bottom line is that either a (former) Mercon type, or (current) Mercon V, fluid will both work. Do NOT use a typical "power steering" clear hydraulic fluid such as what you see from GM or the aftermarket.
How's that for insider info?