Just yesterday a dealer put up a Phnom Penh to Phoenix of Arizona commercial cover on an online auction site. It is claimed that the cover dated 1975.
From the postmark the date and month clearly reads 12th April, if the year is indeed 1975, the cover would be have been one of the last mail out of Phnom Penh before Khmer New Year, airport closed and then the city taken by Khmer Rouge. Last day covers are rare and scarce.
To confirm whether the cover has the last day luck, it is crucial to read the year. The year is actually quite illegible, nevertheless by using computer software to adjust brightness and hue, truth is revealed:
The year reads 1972.
The dealer either makes blind guess, or he lies, hoping this common cover fetch good money.