There is no particular writing task that would be common or frequently appearing in the English-Literacy School Certificate examination. It's amost different every year. In 2003, the writing task was an essay and diary entry. In 2004, it was a letter and a speech.
I was lucky enough to have a letter and a speech as the writing tasks for my English Mid-Course examination (created by my school's English faculty) in 2004. What a coincidence...