[Lynn Eades]

The Aussie track uses a shorter straight plain pin. At the inner end, the hole is smaller. This allows the pin to be punched out, whilst being retained. The other end has a recess with a groove in it. This end is lead plugged. Punching the lead plug in, expands the plug into the groove, thus retaining the pin. The lead is soft enough to fail, when the pin is punched from the inner end.
With English or Canadian track(essentially the same specs) the pins are as per your description. The track sections are assembled into 21 link sections, and joined with pins, that are located with a washer, and split pin I have a number of these pins, and can supply a sample if you wish.
Be aware that the track has quite a tolerance between the links, and requires this side clearence, to allow the track to displace sideways, allowing the machine to turn. The double bogie assembly moves 3/8" each way from centre. I would estimate that the track would need to achieve this over about 16 links (the number of links between the front bogie, and the 2nd bogie wheel)