well a W series box should be fairly easy for you to find
try your local wreckers see if they have supras in there... you can use any manual... 1gge = w55, 1ggte = w58, 7mge = w58, 7mgte = r154 & 1jzgte = r154
unfortunately i don't live in aussie so you'll have to just ring ur local wreckers and parts suppliers
good luck finding the stuff