On IAA we noticed, more by accident than we would have searched for it, a new plaque in the door sill of the driver's door. And we found it as well on the GTC4 as we did find it on the 488 GTB, a model where we definitely had spotted the assembly number at the "usual place" for that car, in the engine bay under the model plaque!
We tried to verify that on the new Portofino, but both cars came from the 226000-S/N-range and the other IAA show cars where from beyond #229000.