2012 GMC 2500HD differential upgraded needed

GMC Bill · April 4

I have a 2012 GMC 2500HD Z71 Extend cab 6.0 gas with 3:73 gears in the differentials. It's factory rated to pull 9,800#. I need to be able to pull 12,000#.

Should I have the differentials upgraded to 4:10 or go to 4:56?

What should I expected the upgrade to cost? Any positive input appreciated.

CamGTP · April 5

Are factory 4.10's rated higher or is because of a towing package with suspension changes?

If you are going to do 4.10's you may as well do 4.56's if this thing is going to be pulling weights all the time. I doubt you'd notice a fuel mileage change because the 6.0 is a gas hog anyway.

I can bet you will pay $3,000-4,000 for parts and labor at a shop unless places around you don't rape you on price like everyone here does. They want like $1,000+ in labor for like a 6-7 hour book time job per axle.

Don't forget about the tune costs to correct the speedo and reprogramming on transmission shift parameters.

Edited April 5 by CamGTP

Grumpy Bear · April 5

6 hours ago, GMC Bill said:

I have a 2012 GMC 2500HD Z71 Extend cab 6.0 gas with 3:73 gears in the differentials. It's factory rated to pull 9,800#. I need to be able to pull 12,000#.

Should I have the differentials upgraded to 4:10 or go to 4:56?

What should I expected the upgrade to cost? Any positive input appreciated.

Nothing you do can legally increase the tow rating of your rig. That said...gearing is a good part of that rating. But so is brakes and cooling. This country was built on the backs Stove Bolt Sixes and Flathead Fords under a 100 hp. You can pull Mount Everest with 5 hp if you gear it deep enough and don't care how fast you get there..

Formulabruce · April 5

IIRC the GCWR should be 14,000 lbs with the 3.73, and 16,000 with the 4.10.

The only reason the 4.11 has more is due to where the torque max is with that ratio.

While truck brakes are important, trailer brakes need to be up to the duty and work with the trucks brakes.

GMC Bill · April 5

1 hour ago, Formulabruce said:

IIRC the GCWR should be 14,000 lbs with the 3.73, and 16,000 with the 4.10.

The only reason the 4.11 has more is due to where the torque max is with that ratio.

While truck brakes are important, trailer brakes need to be up to the duty and work with the trucks brakes.

Thanks for your response Formula Bruce! I use a 16,000# trailer, so based on the numbers you provided, I'm good to go, legally.

I travel in some hilly country locally and make a round trip on I77 thru the mountains in West Virginia.

So, sometimes, the 6.0 gas struggles a little bit. I'm thinking the 4.10 gears would help with that. Thanks again!