Changing from 4:10s to 3:42's... trade me

Hey there, my buddy has a 2006 chevy silverado ss with 4:10's and the lq9 6.0l, he's and older guy and gets 13 mpg on highway since new, i was telling him i think his best investment would be 3:42's most likely i told him i would get on here and see what yalls opinion was... im thinking its a 4+ gain in mileage..
What are you guys thinking? if a good idea im sure someone would love to trade some nice 4:10's for some lously 3:42's helll i would love to give him my 3:73's laying around but he wouldnt like the small notice haha.

I got 2 sets I'll trade ya

set for the front and rear? thats what i need, i forgot to mention this is a 4 wheel drive....

I got two that came out the rear, I don't think it'll work on the front. Maybe someone around here that knows will chime in.

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Originally Posted by jansen

I got two that came out the rear, I don't think it'll work on the front. Maybe someone around here that knows will chime in.

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I believe front is 10bolt rear is 14 bolt.

I'd contact http://www.ronsmachiningservice.net/servlet/StoreFront

He could buy everything he needs cheap!

to tell u the truth i got to do some research on the front axle never split one open nor looks fun to do...

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Originally Posted by BrutalSierra

I believe front is 10bolt rear is 14 bolt.

I'd contact http://www.ronsmachiningservice.net/servlet/StoreFront

He could buy everything he needs cheap!

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i beleaive both are 10 bolts..

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Originally Posted by silverado00

i beleaive both are 10 bolts..

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Your right only the 2wd got the 14bolt rear.

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Originally Posted by BrutalSierra

Your right only the 2wd got the 14bolt rear.

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yep did some searching, both 10 bolt, rear is a 8.6 as we all know and the front is a 8.125

that truck will probably get worse MPG with 342s then 410s. get him a tune and a fresh tune up and his mpg should raise up

i ve also heard that. i think he has enough power to be alright in city driving.. it is a 345 hp motor,, not like my procharged 5.3l but i thought 3"42's was a good number,,
what makes you think of worst mileage?

weight of truck and 345 really isnt all that much...i wouldnt touch that truck, just have a good tuner dial it in

3:42 would help on the highway,probably make it worse in the city

not necessary true, as the weight of the truck and depending on the rpms where the 342s land the truck it may be lugging which will cause worse mpg. best fuel economy is usually around 1800-2100 rpms crusing

ive gotten better mpg with 410s vs my 373s in the past

alright you have me talked out of it,,, last time people on here talked me out of welding my rear end, man i wish i would of listen,, 1,200 dollar tires wasted and well yea very exspenive trial, im 21 so im hard headed,, Quik... i see your boosting,,, im ditching the procharger soon, and i want sts turbo, but considering waiting till i drop a 6.0l i first since the 5.3l is pushing 218,000 miles,, looks like your very knowledgable on boost,, i read through some of your other post,, ill have to get with you if i find my self confused,, but for the most part ive delt with it quite a bit, i boosted a 408 couple weeks ago,,