While the specific phrase "the directors dirty little top" appears to be a slight variation of it refers to a specific installment in the Mystery Mail lineup.

: Boxes typically contain a random mix of electronics (Rokus, antennas), household goods, clothing, jewelry, or "tat" (low-value items).

The Eng Mystery Mail scandal came to light when a group of concerned investors, who had been receiving the mailings, began to investigate the company's activities. They noticed discrepancies in the company's financial statements and became suspicious about the lack of transparency in its operations.

Elias realizes that the "Mail" aspect of the mystery comes into play when he finds a hardline transmission log (an old-fashioned "mail" drop) hidden inside the hollowed-out gyroscope casing. It is a receipt for the tungsten sale, addressed to Halloway but sent via a dead-drop