Diff Fluid

Have a 2004 with 55,000 miles. I want to do a little preventive maintaince and I want to change the front and rear diff fluid. I have already done the tranny and transfer case.
What is the capacity of the diff? Is it an over kill to replace the fluid in the diff? Not experiecning any problems. Jsut want to give the truck a little TLC.

Thanks
Paul

Might be a little early to change the diff fluid, unless you have done a lot of off-roading or towing. What color is the fluid. It should be an amber color, it it is getting dark then you may want to look in to changing it. I would recomend changing it with royal purple max gear 75w90.

2.5 litres in the rear and 2 litres in the front diff.
I'd use only GM's 75W90 synthetic gear oil. None of the other stuff out there meets their spec for the rear diff that i know of.

Thanks for the info!!! I have not looked at the fluid yet. I dont do any off roading or towing. Just wanted to do some preventive maintaince on it.

Mobil 1 diff fluid is approved for the rear.

Is Mobile 1 approved for the front as well??

I used it in my truck, it meets the GM Ilsac specs. They do not specifically recommend any alternative lubes, they say must meet ____ specs.