2005 6.0l 3.42 needs rear end - options?

I've got a 2005 Avalanche 1500 with 285k.  Husband dropped a 6.0l from an 03 2500hd in it.  New tranny at 230k.  It's paid for (obviously), pretty (mama's truck), and comfortable.  I get 19 mpg with the 6.0l and 3.42.  Husband gets a little closer to 14 when he beats it borrows it.  Realistically, we'll never sell it and are not afraid of dropping money into it.  It needs a new rear end.  He'd rather replace the entire axle.  It's overdue, and he wants to just take care of it all at once.  I'm not sure what all matters so: GU6, without active brake control, 4x4, Z71.  I rather enjoy embarassing the little boys who have no idea what they're sitting next to at the lights, so take that into consideration.  Any recommendations on what to look for or stay away from?  TIA

3.73 is a good all-around gear. If uou don't mind giving up around 1-1.5 mpg a 4.10 is a lot of fun off the line. My 02 had 4.10s.

Husband had said that the front needs to be done too, it has the push button auto and we've always had problems with it, not that we ever used that mode.  I'm interested in making it more fun; for the amount of miles I put on it, the fuel mileage is only a measure of who's nicer to it.    Sounds like it might be a good time to go for it!  Ultimately, whatever we do to it, we only want to do it once.

He's no stranger to the occasional mod...

Go with TrueTrac.  Don't need to replace the entire rear axle - I've got over 310K miles on my axle with a TrueTrac installed.  Stronger than the G80 and works well on snow as well as blacktop.  Have had one in my truck now for 7 years.  And as MyBigToy says going with 3.73 or 4.10 gears will just add to your fun.

In my opinion the, the primary consideration should be WHO you use.  Setting up a differential properly is critical to longevity and performance.  Stick with a drivetrain expert in your area that has a good track record.  I agree with the Trutrac suggestion, probably the best all around traction solution.  As for lower gear ratios... your mileage may warrant a full rebuild, with that extra cost may not be an issue.  But you will have to match the front of course, so that is likely double the cost.  Good for you to keep your truck on the road! 

For a rough comparison, my 2004 EXT has the 3:73 gears front and rear (single speed All Wheel Drive instead of the 4 wheel drive in your truck) and the LQ9 6.0l High Output engine.

My long term average MPG after 200K miles is 14.17.

This truck will get up and go just fine, but I mostly drive it like the old man I am.

I'm thinking 2000 RPM is about 70 MPH at cruise.

Maybe that is helpful, maybe not.

mcintyrerj said:

Husband had said that the front needs to be done too, it has the push button auto and we've always had problems with it, not that we ever used that mode.  I'm interested in making it more fun; for the amount of miles I put on it, the fuel mileage is only a measure of who's nicer to it.    Sounds like it might be a good time to go for it!  Ultimately, whatever we do to it, we only want to do it once.

He's no stranger to the occasional mod...

Click to expand...

Time for an SAS swap with blower.