My differential cover gasket is leaking

SOURCE: I have a 2003 chevy silverado, with quardasteer.

I have had this problem before.. change out the rear diff. fluid with fresh fluid.. note: only use quadrasteer rear diff fluid only purchaseable at a gm dealer..

Testimonial: "I had the dealer change the fluid, it still makes a little noise,but nothing like before. Is there a second idea? Thanks."

SOURCE: 91 chevy k 1500 rear axle wheel wobble

It sounds like you rear and pinon gear

SOURCE: Humming noise in front end of truck

I'm having the same problem with my 2006 Chevy 2500 duramax...The humming starts at 25mph and then gets less prominent and then at 50mph it gets more prominent and louder, then at 60mph you can hardly hear it.....I did notice a little bit of leakage where the front axel meets the from diff on the drivers side.
Any suggestions?

SOURCE: Im slowly leaking differential fluid.

Definitely replace both axle seals at the same time. It will save you time and money in the long run. When the axles are out be sure check for wear on the axles where the bearings make contact.

SOURCE: vibration in steering wheel and pulls to the right

Check your front brakes. You may need to grease the caliper slides and machine or turn the rotor. If the rotor is warped it will cause a vibration in the steering wheel, you'll notice it more under varying braking conditions. The caliper could be sticking which can cause a pull. As for the squeaky rear end, being a car that old its time to replace the rear bushings. If they are greaseable then just regrease them. If you replace them consider going with urethane or polyurethane bushings. They will give a better ride than the stock rubber bushings. If the new ones come with grease fittings make sure you grease them at least twice a year, but at every oil change would be wise.