4th Series B20 project came with a badly damaged grille. I have two others that are less bad but am still on the look out for something better.
Over the past few years I've found that you need to carefully check sellers' descriptions, and so have become used to counting the number of verticals and horizontals on the rear parts of these items to avoid buying the wrong model. This one at a glance looks like a B20, but it has too few vertical divisions (11 each side rather than the 12 that I've counted on 'correct' Aurelia grilles), so I asked the seller for a photo of the rear...
... which shows two pins as the upper locating mechanism, confirming my suspicion that it was Appia, not Aurelia.
It's easy to make expensive mistakes if your enthusiasm gets the better of you!