Attaching the grill is problematical. The grille mounts to the headlamps and the center grille brace. none of that stuff lines up properly. It could be scabbed in if you don't care how good it looks.
Pic 1: Current set-up (My rig is a '90 and the PO had put on the sombrero logo grill(e)).
There are five spots where you can secure the grill(e) with screws and another pop-in place (will follow later)
Pic 2: Top right screw point
Pic 3: Top left screw point (This pic actually shows all you'll need to see the difference between the two types of grilles in terms of installation/construction difference) You see the gap between the grill(e) and the headlamp extention where the securing screw needs to go?
So even if you're going from the new to the old "TOYOTA", I believe you'll encounter the same issue of not being able to utilize two of the five screw points.
You'll still be able to use the upper two, the middle (lower) screw point, as well as the clip in the middle which should be strong enough to secure the grill(e) in its place.
HOWEVER, I have noticed that the lower part of the grill(e) tends to wiggle around a lille, so it might scrape the paint off of the painted part below the grill(e) same piece where it showed some rust earlier.
Anyway.... a long winded answer to such a simple question!