FOUR ''musical'' birthday cards posted from Hong Kong to Australia contained more than good wishes, the District Court heard yesterday. But the cards failed to get past Customs officers in Sydney when it was found that each one contained almost five grams of heroin mixture instead of a musical device. The cards were contained in a parcel addressed to a Miss Trudi Tuckwell in South Coogee, Australia, the court heard. Leung Yat-wah, 43, had pleaded not guilty to trafficking in a dangerous drug, possessing a dangerous drug for the purpose of unlawful trafficking and possessing a dangerous drug. Yesterday, Judge Britton granted the Crown's application for the forfeiture of $136,000 cash seized at Leung's flat. Although Leung said the money was partly the proceeds of his money-lending business, Judge Britton said Leung was unable to substantiate his claim. Leung was earlier jailed for a total of six years. Prosecutor Charles Chan said a sample of the drugs was taken from the cards before the parcel was reconstructed and delivered by the Australian Federal Police to the address on September 24, 1991. Police searched the premises and retrieved the cards. Also seized at the premises was a receipt for the telegraphic transfer of A$750 (about HK$3,890) from Trudi Tuckwell to Leung's bank account in Hong Kong, the court heard. On November 2, 1991, Hong Kong police located Leung at a Jordan flat where 0.83 grams of cannabis, 13.03 grams of heroin mixture and packing paraphernalia were found. Also found was a musical card similar to those sent to Australia, three musical devices removed from greeting cards and more than $136,000 cash.