Would gas mileage improve going from 4.56 to 4.10 gears 72 K10 with 35s

[fishmunger]

Have a mostly stock 72 K10, 350, auto with 35s and 4.56 gears. It takes a lot of RPMs to go down the highway. I'm wondering if it is worth going to 4.10 gears, if it would actually make much of a difference fuel economy wise. Reason I ask is, I am probably going to have both front and rear axles rebuilt, and that would be the time to swap the gears.

I'll be using the truck to frequently tow my 4000# boat (mostly highway), if that matters. I would think 4.10s would still be low enough to not be sluggish around town?

I don't have any plans on going to an overdrive trans.

Thanks for your opinions!