Hey, i always thought my rear-end was geared at 3.73.. Now i'm not so sure.
The truck has the 68rfe transmission.

How would i find out?? I have the window sticker, & all it says is 11.50 rear axle, Anti-spin. It is an AAM, i seen it stamped on it.

VIN# 3D7-KS29A27G-783344

Thanks,

Chris

 

4.10 is a $50 option on the window sticker. If it isn't on the window sticker, it's a 3.73 gear.

 

sabresix: thank you. i don't see it under the OPTIONS on the sticker. It must be the 3.73's... I thought it might have the 4.10's because the fuel milage. I guess it has been getting better, it get's around 16mpg from a tank . I was hoping the milage would increase after just getting past 20,000.


Any ideas on how to up the fuel mileage?

Thanks,
Chris

 

Chris, the cummins diesel is still considered being "broke in" until you reach 75,000 miles or so. (If I remember correctly) If you want to facilitate the break in process, find a heavy trailer and tow it around. I believe that will help improve your fuel mileage a bit...then again I do think the 6.7L will only do 16-17 mpg. Still pretty good for a big heavy truck.

Scott

 

Get a Smarty and delete the DPF/EGR. More power and MPG; have your cake and eat it too.

 

stock tires? 1600rpm is around 65mph? If so, 3.73 gears.

As far as upping the mileage, unplug the EGR. If you want to take it a step further, mega-engr has you covered. Deleting the DPF, NOx adsorber, and Cat will yield some good fuel economy gains and adding the Smarty will yield even more. At 56K miles, my '08 with 35" tires is getting 18-18.5mpg in my normal 50/50 city/highway weekly commute and will see 21mpg on the highway.