Jamie,
That ECU came from a GS121 Crown, 8509-8512 specifically, but it will also fit in the 8512 to 8609 and 8609 to 8703 versions as well.
Can you tell me the colour of the plastic the loom plugs plug into, (yellow or grey I think), and the Pin numbers, something like 24p / 10p / 16p or thereabouts.
Thanks,
Mitch.