Ha ha, I have the sew-on patch from the '74, looks the same as later badges.
At 17 and 9 month I rode my TS185B from Frankston to Hattah, on L plates, to the '74 event, AND RACED; no luggage or tools, I rode with a friend, who also raced on a DT400B, we slept on the side of the highway in our leathers & helmet.
There was all this hype about bikes running lean on the needle and seizing after running flat-out on the salt-flats, when I was flat-out on the salt-flats my TS started slowing; I thought 'fark I seized it!' but the rear tail light had dropped off and the wiring loom was getting wrapped around the rear wheel, LOL.
I was running second in the 'up to 200 trail class' when I got a rear puncture (with a trail tyre - bad news!), had to ride the last 100k loop with the flat, ended up finishing 10th.
Had to bot a lift home to Frankston, what an experience!