When Utsch got the contract for the 1978 series plates in Saudi, they made hundreds of test plates, test designs and salesmen’s samples. Two of these plates were given to collectors who visited plate factories in other countries where the salesmen had left them as trade samples.
All of these are private plates and all should be black on white. The black border and revalidation stickers were only used on the very first few plates issued. Number blocks are reserved for different classes of vehicle in different regions and some of these are wrong. All are mint.
3285280 and 353371 are actually on the wrong bases so they may actually be copies or outright fakes.