It's a 56A 5 speed. Great behind an A12, put it behind a bigger block and you might find yourself with less than 5 available gears.

Small gold mine? Not really. Once you count in shipping costs you will lose most of your potential buyers, and the only way to offset that is to drop the price much lower than what you would see it sell for here in Aus. Sell the whole engine, don't split it up. There are very very few complete GX engines around the place.