Changing differential ratios?

The rear axle is about to come out on my just-bought 07 Tundra Limited. (just posted about the issue of wheel bearing replacement).

Is this an opportunity to change diff ratios to seek out better fuel economy?

My usage of the truck will primarily be with it loaded with tools & materials, moderate loads. When I do need to tow, it will be something like a chipper (circa 5000 lbs) over a distance of just a few miles. So I feel that this gives me 'permission' to see if I can push some more wheel revolutions per engine RPM. But this is all unknown to me.

Since my rig is 4WD, I would of course need to redo the front diff.

Has anyone else been through this?