I think 3.73 would make a noticable difference....several years ago my 03 Burb with 3.73 was in the body shop after a accident, our rental was a 05 Burb with 3.42 that we drove from Texas to Indiana & back over the holidays and there was a pretty big difference.

The 03 on the same trip gets 14-15mpg loaded down with 2 adults, 4 kids, and a mountain of luggage.

The 05 got 17-19 mpg on the same trip.

If you can find a good deal on a set of gears I'd say it would be worth a shot.

 

i did a little searching last night & it does seem they make 3;42's for the 10.5, just not sure if i got the sf or ff rearend.

 

Only the 9.5 is a SF the 10.5 and 11.5 are both FF.

 

Assuming you have a 4L80e...

70mph w/ 4.10s = 2300 rpm
70mph w/ 3.42s = 1900 rpm

Used this calculator...http://www.f-body.org/gears/

It may not be worth it. The RPM change is fairly minimal.

 

I going off the 70mph to the 60mph differents. I wanna say its 2350-T/2150 and it made a big mpg difference

 

Might be worth a shot then.

I know there would be more load on the engine w/ a 3.42 vs. the 4.10 to get up to speed, but as far as maintaining it, its hard to say. If your commute is full of elevation changes, you may actually not gain anything, with the truck having to downshift and/or increase throttle percentage to maintain 70mph.

 

I wasn't planning on going with the 3:42's. I do make long hauls pulling cars,trucks & tractors. I get about 12.5 pulling my truck on a 20ft car hauler. Was just really looking for a happy medium. Maybe I just need a Allison lol

 

Haha. I gotcha! 3.73 may be that middle point you are looking for .

 

and a desiel... LOL

 

My buddies have been looking for me one wrecked. Then I would have a spare engine for the race truck lol.