I've been talking with some companies to make a custom differential, but it's slow moving.
Yeah...its not just us. I think several others have thought the same thing...that would be the deal for sure.
On the Toyota gearing thang...I think you would like 4.88 gearing. Since that's the lowest matchng combination, I would pick that over a mis-matched 5-series. My 37"s work good with the 5.13s but I've already decided the next project with be 4.88 geared on 35" tires. I can make the truck sit lower on 35"s and that's my big push to run smaller tires and gearing on the next one. I think the off-road ability would only suffer a tad, and the lower cog and higher gearing might make it more practical for a daily driver.