The Louvre is a grille that fills the large hole in the front bumper. It has 13 vertical round bars that taper to a blade at their rear, and a hole on its left end for the temperature sensor.

In my cars, I have painted the round portion of the bars silver as well as the three small grilles that fit in the small holes in the bumper. These silver highlights mimic the grille and headlights of the 850 and add a bit of contrast that new Volvos sadly lack IMHO.

If you look at your air guide, you will see a t-shaped hole near the center of the bumper and two vertical sockets, one for each end of the louvre.

It is possible to install the louvre without taking the air guide off, just slide the louvre into the hole and wiggle it up and around to slide its ends down into the slots in the air guide. After the louvre is in the slots, its middle can be pushed so that the tab in its bottom fits into the t-shaped slot in the air guide.

I always check to see if it is in place after service, as it could be left aside when the air guide is installed on the car - not much holds it in place.

I have taken a picture, I'll post it as soon as I figure out how to do it. I'll email it to anyone who wants it.
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3 8s & 2 7s 740,000 miles total