Ade, fascinating pictures of the bottom of your car!
I did not know that those louvred panels each side of the engine ever existed!
I checked the parts book, and they are in Tav. 62, pos. 22 and 23, Grembiale destro e sinistro completo (a richiesta) - so it was an option - does it appear on a period price list, I wonder?
There is one type for the LHD, and one for the RHD car! With two small closing plates, pos. 19. and the necessary screws, pos. 73!
Grembiale could be translated "Apron".
I wonder who ever specified this option on the purchase of a B12 berlina.... and how many of those are still existing today..!
I shall from now on check all B12 to see if I can find another one so equiped!

Well done!
PS: The gaiters on the rear leaf springs are also interesting - I have the same on my Lambda, now I know who produced them!