It depends on what gear ratio is in it. The way you figure reduction is.....tranny gear ratio X tcase ratio X tcase ratio (since there are 2 tcases) X axle gear ratio
So assuming the 2nd samurai tcase has stock gears in it....if left in high, it would lower the overall drivetrain ratio 1.409 times more, compared to having just one tcase.....if put in low it would lower the overall drivetrain ratio by 2.268 times more, compared to having a single tcase.