Monteverdi Sierra bonnet air intake ?

The MV Sierra does have this specific air intake on the bonnet. Its size is 84 x 13 cm. Does any of you know from which car it has been sourced?

Update 13-1-2019: I also posted this question on FB and someone remarked it was sourced from a BMW 5 series E12. Upon checking I found out it was on a 525 or higher ie 528.

http://bmwteilekatalog24.info/Classic/P/E12/Lim/525/ECE/R/M/1980/06/47157/51/51_0705/51131819856

The part number is 51131819856 and labelled as Ziergitter Lufteintritt

When I checked Ebay I found a NOS, unfortunately both edge were broken off. But at least I could verify clearly it is indeed exactly the same