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Steve, ASE Certified Technician
Category: Chevy
Satisfied Customers: 3419
Experience:  ase master tech over 25 years
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04 silverado 2500: rear diff..Duramax..Gasket..I think drain plug

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I have a drip from my rear diff cover on my '04 Silverado 2500HD (Duramax). I guess I need to replace Gasket.
I think drain plug is 3/8 square socket - haven't tried yet. Auto parts store said fill plug was 13MM or 15MM. Also said I definitely need a torque wrench to replace bolts or I run the risk of breaking bolts.
1. Do I need torque wrench?
2. Specs - how much torque required?
3. any specific order for tightening the cover or just criss cross?
4. Rear diff oil? 75W90 Synthetic sound right? How many quarts?

Guy at the auto parts store kept looking stuff up in manuals and if he could not find my truck he used specs for a Ford?? Not a lot of confidence in him!

Depending on which rear axle you have the capacity is between 3-3.17 quarts and does take synthetic gear lube. A torque wrench would insure that all the bolts are tightened the same amount for less chance of leakage.

The bolts are to be torqued to 30 foot/pounds

Customer: replied 5 years ago.

I have not looked yet, but will I be able to acces thefill plug or will I need a pump?


How do I know which rear axle I have? Bought truck at auction for y 16 year old son. I paid $3,800 -it has 132,000 miles. I a just trying to fix it p for him.


I am not familiar with cars or terminolog,but very handy - carpentry, plumbing and electrical work mostly.


Three weeks ago I changed the upper control arm and ball joint on the passenger side. Also did front wheelhub bearings and breaks and rotors all around. I watched a You Tube video! then took the truck to get new tires and an alignment.

the fluid bottle usually come with a top you can attach a small piece of hose to in order to fill the differential back up.

There should be a tag in the glove box with a bunch of option numbers on it. The parts store should be able to tell which differential it is from the option number.

Sometimes YOU TUBE can be a big help!

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