i had 04 reg cab, and i know it was 4.10 gear ,now with my 06 reg cab it's 4.56, i can tell how it gets off of line quicker, but when your in 6th on highway at 75 mph ,how much more petrol i'm i using compared to 04? i have had 06 for 8 months and only 800 miles on odmentor, so can't really tell so far. and one more stupid question, i thought dana 60 rear end was badest they made for our power we make, any way i keep hereing about cars with 12 bolt rear, and how strong they are, and i looked at mine and saw maybe 9 bolts? spare was in the way, any how could someone help dumb Texan out? and on my 04, used magnaflow system, but this time ,i cut second cats out ,the first had 02 sensers so left them in place, then i put x pipe on, and after that used cherry bomb type mufflers from magnaflow, run my pipes to rear and cut out resonator and welded tips back on, really sounds wicked!!!! but concerned about inspecton time, i have cats, andround straight 16 inch magnaflow on each pipe, i'm i still legal? hate to waste money on changing pipes again, just thought someone here could help. Thank you for your time and knowledge because i'm not that clear on things.

 

The amount of additional fuel will be minimal. Your gas milage will can be affected more by how you drive it vs 4.10 to 4.56.

 

A 10 bolt or a 12 bolt was a way to distinguish GM rear ends. The bolts mean nothing in the way of strength. the 10 bolt axles had 10 bolts in the cover, the 12, had, well 12 bolts and were much larger and stronger then the 10 bolt. But a 12 bolt has a ring gear diameterof 8.875" where a dana 60 has 9.750" diameterring gear. It's been called the flying anvil because it's big, heavy, and indestructible. Bullet Bob Reed runs a 60 in his drag car which turns low 8's in the quarter.

 

I changed from 4.10:1/stock and went with the 4.56:1. Much better in traffic for me.
Tends to keep her more in the sweet-spot..... I think there 12% lower.

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