If the air curtain duct design on the new Ranger is similar to that of the F-150, it's separate from the bumper cover--which won't fit your 2003 without modification anyway. The F-150 is the only vehicle on the American market that uses a horizontal inlet for the air curtains, with the intake sitting between the headlight and the top of the bumper cover:
What you should do is order a couple of those and fit them to your Ranger, which should be both cheap and easy. I have Hyundai Ioniq curtain ducts on my list to buy, at $6 each, to fit to my Prius.