I'm looking to purchase an 05 Z71 with the H.O. 5.3 in the next few days and need to get some opinions on what rear end to get. This will be my daily driver and will see about 50 miles a day with half of that being city. I don't plan on racing or modding the truck, nor will I be towing. I have a good idea about the performance gains that the 4.10 will bring, but would like to know what kind of mileage people are seeing with them. I currently have an 04 crew cab and average about 16 mpg with the 3.42, so I assume that it will be similar with the new motor. What about the 4.10, will I likely see 12 or 15 mpg?

 

Can't speak to pickups, but I lost 2 mpg freeway (19 -> 17) and 1.5 mpg city (15 -> 13.5) going just from 3.73's to 4.10's in my Avalanche. While the extra off the line torque is quite handy, I hardly need it (with a Radix) and would actually rather have my mileage back.

I know you can't get 3.73's in the new trucks, but I think it is the ideal gearset with the 4L60E. If I were you I'd be tempted to get the 3.42's and a tight, higher stall converter for some off the line power. On the freeway it would lock and your good 3.42 mileage would take effect.

What speed do you drive on the freeway? If you can't go higher than 60-65 mph then the 4.10's would work (~2K rpms). But, if traffic goes 75-80 mph, you're gonna want the 3.42's IMO. Good luck with your decision.

 

I have 3:73's in mine

 

if you don't plan on modding 4.10's will be a nice gear. Of course, tire size and driving preferences will play a role in your choice as well. I have 32" tires with 4.10's and love the athletic feel of that set up.

 

I've heard the L33 only comes with 3.42's or 4.10's.

 

He asked about mileage....

 

mileage wise, with my 4.10's, 32" tires and a 2500HD, I see 12mpg city, 14.5mpg highway @ 75-80mph averages.

 

3.42's, 4.8L, in a 1500 I have seen a high of 23mpg and a normal highway of 20mpg.

 

3.42 in my 5.3 ECSB, and I usually get around 17mpg. I do run a little bit shorter of a tire in the winter. I like the 3.42's and wouldn't think of changing them.

 

I average about 14.5 in mixed driving and 15.5 on the highway. I wouldn't trade the 4.10's for 3.42's.