its not all that hard to swap out gears. If you have some knowledge about gears. maybe about 2 hrs per axle. (thats with beer breaks and laughing at your friend because he just smashed his hand in the gears) doing a complete axle swap would be more labor intensive. unhinging the leaf packs, taking out the U-joints and moving that 600lb things from one truck to the other and thats only the rear axle, the front would be twice as long.

 

I have 3.73 and I'm pulling just over 2500 RPM at 80mph. Gear Vendors unit looks really nice but it's pricey & you need to cut your driveshaft.

You can lower RPM's by approx 200 by going to 315's but I don't know if 315's clear on stock suspension. Been considering doing that myself but for now I just drive a bit slower.

Seems to me that when people talk about big tires dropping gas mileage they're putting on some big tires. I drive around country roads for the most part and lots of highway miles and the only thing that kills my mileage is driving over 2000 rpm. I can drive around all day and get an indicated 25mpg at 45-50mph. Don't know how accurate the overhead is tho.

So from what I've seen if I go to 315's, yeah they're heavier but they'll fit on my stock wheels just fine and according to the spreadsheet they'll drop my rpms by 200 which puts me at 2300 at 80mph which should help a bit. Instead of running 17.5-18.5 on the highway I may be able to get 1-2mpg? Or maybe I can run 75mph and get a little better. Seems to be the cheapest & easiest thing I can do for a little bump in eco. Wish my 6 speed was an 8

Only thing I can see is that I may need a leveling kit to get away from any rubbing.

Spreadsheet is called 'gear-speed-calculator.xls' if you can't find it via search send me a PM & I'd be happy to email it to you.

 

http://www.florida4x4.com/tech/gearcalc.php
this is the coolest ratio calculator ive found...

 

Silverhoss99 where are you located, I was thinking about swapping out axles due to possible upgrade of campers.