I just bought a 2006 silverado 2wd 1/2 ton extended cab 4.8L engine 4sp automatic transmission with a 7in pro comp lift. 4in lift with 3in blocks. The tire size is 315/70 R17 and the gear ratio is 3.23. I would like to change the gears out for better performance when passing cars and entering the freeway. I was told by 1 shop they would go with 4.11 or 4.56 both with posi and another shop said 4.56 with posi. The question I have is what gears would be the better choice for a city and freeway driver only and not make my rpms run high on the freeway. Thanks in advance for the help.

 

IMO do 4.56s(I did motive gears) with a tru trac posi. Would be the best setup for city power, will make you run around the 2k mark on the highway as well.

Gonna want to do a custom tune when done, or at least have the speedo recalibrated for the gears and the tire size

 

country_09,
The motive gears with a tru trac posi set up is exactly what one of the shops recommended for my truck. What do you think about using a superchip or diablo tuner for the custom tune?

 

Great gears and even better posi unit...and I'd do a real custom tune. Not a programmer. Contact blackbearperformance.com or gowheatley.com, or see if there is a place around that does dyno tunes with a good rep to back it up