I went from 3.42 to 4.56 at the time i was running a 305-45-r22 tire, it was a big difference for sure. But now that im running aluminum 17's it is one hell of a difference. But in a good way. Doesnt take much for them to start spinning of the line.

 

with the 411 gears how much mileage did u lose?? i been thinking about going from 342 to 373 in my truck. i do a lot of highway driving and it just runs better and gets better fuel mileage at like78 mph then it does at 70

 

Please excuse my lack of knowledge on the topic. So on my truck, AWD 6.2L Denali, it came with 3:42s. I do alot of highway driving and spirited driving as well. Will 4:10s or 4:11s be okay for me. How much will this hurt my milage? Is there a difference on 4:10s and 4:11s? I currently have the stock Denali 20s but plan on buying the CK375s for my truck. They are 22s and was thinking of using a 305/50/22 on them. I dont want it to feel like a hog thou. Thanks you for your response.

 

4.11's will wake up those heavy 22's for sure. I haven't decided yet on mine lol...

 

Do 4.10s. It will really wake it up and the fuel economy loss (if noticeable at all) will be minimal. The cost of going from 3.42s to 3.73s is not worth such a small change in gearing.

 

The carrier and ring and pinion are for an 8.5 however the bearings are slightly larger so they called it an 8.6"
So just buy everything for a GM 8.6" 30 spline and your set

 

Approximately 200 rpm on the 4.56 more on the HWY. I would stick with the 4.10.

 

4.10s are the best to get the truck out of its own way on heavier wheels or 33s. 34-36" tires need 4.56s for the same purpose. For performance, 4.56s on heavy wheels or 33s, and 4.88s on 34-36" tires.

 

I am going with 4.11's next week. I am not planning on going bigger than 285/45/22 and if I do return to 18's or 17's, the 4.11's will be perfect imo with 30-32" tires. I have noticed that adding 22's has caused my tranny to downshift out of 6th gear more I guess due to thier weight? Anyways, 4.11's should fix that.

 

Keep us posted on your impressions of the 411s. I have been bouncing around the idea of long tube headers or gears for a number of months so I am very interested in your results. I absolutely hate the 3.42 gearing in my truck...especially when towing a decent sized load. I have been trying to decide which one to do or whether to just forget it buy a new duramax instead and build it up.