I emailed Nitro about 4.56 gears for the front and here is there response:

There’s hardly enough demand to justify the 4.10, the only way we could make it happen is with the overseas crowd (mostly diesel) and 4.56 is way too low for them. We have no plans to offer 4.56 any time soon, and I’m certain nobody else will ever do them. What I’m getting at is don’t hold out for 4.56.

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There advise was if you want taller gears go with the 4.10 because there may never be anything else.