Ok, for anyone following along, the parts have come in. The newer style 2nd gear measures up to be the same as my original older style (apart from the synchro area), so thats a good start. The synchro is a completely different design (3 piece) and the inner diameter is smaller to suit the newer 2nd gear. Unfortunately, the spring/key arrangement is also different. I should have realised this when looking at the diagrams and pictures, though most of this I'm doing after work, late at night, so I blame my brain for being half asleep.
So I now need to order the synchro on the other side of the hub and the appropriate springs and keys.
In the above image, the original spring/key arrangement is circled in red. The new style is in green, and the new synchro I need to order is shown in orange. Hopefully this is all I need to get this thing back together (and working).
So far, 2nd gear and the matching synchro has cost me an extra ~$180aud and I received it within a week of ordering. I went to my local Toyota parts dealer and they quoted me over $400+aud just for the 2nd gear, with a 4-5 week wait from Japan. I'm not even going to bother checking pricing with them this time, as I can see a few local companies selling the synchro for $130aud and the keys for $8aud EACH. I'm about to place an order for 3 keys, 3 springs & 1 synchro, with delivery for $64.80aud.
Part numbers as follows;
3336535060 - Synchro keys (x3 req'd)
3336735080 - Synchro (x1 req'd)
9050108158 - Springs (x3 req'd)
