gear ratios. should I go 4.10 or 3.73

[Pampas56]

My truck is a 1989 K2500 ECLB (light duty 7600 gvwr/6 lug rims) with 5.7 TBI and 700R4 trans. It will be used for general hauling, light towing (2 to 4K with the RARE 5 to 6K load). 4X4 is for snow and muddy fields, not trails. Maybe some time on Forest service or logging roads.

I bought parts to rebuild the front and rear axles from the lug nuts all the way to the drivelines.

It currently is 4.10, but I bought a 3.73 front diff and gears for the rear axle.

Will 3.73 gears give me better mileage/performance than the 4.10s it has now? I calculate my mileage as 13mpg +/- half a gallon with the RARE high /low tank.

I am not worried about the cost of the parts, they are already bought! Just curious if one is better than the other for my usage.

If some of you folks could give me an idea what your 19' long 4500 lb. truck does with YOUR gear ratios, I would greatly appreciate it.

Also any insights will be read!

Thanks
Steve