what rear gear?

Can anyone tell me what rear gear is in our 2012 GMC Sierra half ton crew cab 2WD? Here is the tag in the glove box:



Thanks.

Scott

[FED 387]

not positive but RPO GU6 is a 3:42 rear axle ratio in a Chevy/GMC truck-better check with a dealer to be sure----FED 387

Thanks. I did double check with the dealer and you're correct; 3.42. When we purchased the truck it had 245/70/17 tires.



When the tires were needing replacing we went with an OEM wheel and 275/55/20 tires.



Even though the circumference is only 4.4" more I'm really surprised how lazy the truck is now. Acceleration is noticeably less and power seems down. Maybe I'll need to look into 3:73 or 4:10 gears?

Scott