I remember it well. It was in 1985 and it occurred on a Sunday morning. I was a young pioneer at the time. I was no where near Sydney but we heard about it when we got home from the meeting at lunch time. It was all over the news. I remember being fired up with expectation that the great persecution was beginning. That was the talk anyway. Immediately afterwards, for a couple of years, there was a policy of checking the halls before letting everyone in prior to each meeting.
The hall that was bombed was the Casula Kingdom Hall and the congregation involved was the Lurnea congregation. The hall was used by several congregations if I recall correctly. These are suburbs in western Sydney about 30 km or so south west of the cbd.
A year later I went to bethel. Lurnea had quite a few bethelites assigned to it as it's pretty close to Ingleburn, and so many were there at the time of the blast. I got to know a number of them very well. No one from bethel was killed, but all were injured in some way. Most of the injuries consisted of cuts and abrasions and perforated ear drums and were only relatively minor. But one bethel sister was very badly injured. She had to have her face reconstructed.
As far as I know, no one was ever convicted of the bombing. The talk around bethel at the time was that the police knew who the perpetrator was but were not able to pin it on him. It was widely believed that it was the unbelieving husband of a sister from the congregation.