I'm one of those guys who checks mileage every fillup and I noticed something quite strange. My city mileage only differs from my highway by about .5 mpg!! Truck is an 06 six speed with 2,500 miles, and gets almost 19 around town, however gets 19.4 on the highway!! I'll admit, I baby it big time putting around town, and drove 150 miles doing nothing over 72 on the freeway. I'm pretty sure I have 4.10 gears, but how do u know the ratio for certain? Those numbers are unloaded of course; but my question is, are all 06 six speed fitted with a 4.10 gear because at 60 mph I'm at about 2,000 RPM which seems extremely high. Thanks in advance

 

You probably have 4.10 gears since my buddy has a 6 speed and his truck does 70mph @ 2k rpm and he has 3.73 gears...

 

look in the glove box there should be a sticker on it with all that on it ,will tell you if it is limited slip or not also

 

My 02 6 speed had real similar hwy/city milage.

My 06 with 560 miles on it, auto and 3.73s got 18.1 on its first tank. The computer says 18 so I'm confident in it. I baby it too.

 

My '06 has the 4.10 gears. At 75 mph I'm doing right at 2400 rpm, and I averaged 17.7 mpg for 2100 miles on my last trip. I've only taken the one trip unloaded, but loaded I'm averaging 13.2 mpg.

 

Actually, trucks equipped with the G56 6spd is only available with the 3.73 ratio. The G56 overdrive ratio is equal to the older NV5600 6spd tranny with the 4.10 gearing.

MikeyB

 

Thanks, I'll check on that.

 

G56 is the 6 speed in the 06s and only comes with 3.73 no exception period. I did notice that the 07 cab n chassis you can get 4.10 with the g56 man what a slug that must be top speed 55mph