Sorry. Most refer to it as a "lower valance".
I gave up looking for early V6 options....there simply was not many, and none that offered the Boss type valance and splitter that I wanted. After searching, I gave up, and bought a used GT front bumper cover, grille, and lower valance.
Lots of GT options in this area, but of course it will cost more to convert first. I bought a good used GT bumper cover, and cashed in on a favor that my son owed me (he is now a manager at a auto body shop) for the painting. The lower GT valances are plentiful on ebay, so that helps. And by shopping Ebay, I found a Boss splitter for 30 bucks, new. I had to buy the bolts and C-clips from my local Ace HW store, plus some of those plastic plugs (NAPA).
So, I'd say it depends on the style and price you want to go with as to valance choices for your V6 Mustang