What makes a front end shake on a 2004 GMC Sierra 1500 4X4?

The very FIRST thing you should do is MAKE SURE the lug nuts are tight on the wheels. The next thing I'd recommend is to closely inspect the tires and make sure there isn't a bulge... or isn't some kind of tread separation. Good luck...

the front wheels may need balancing or it could be a loose or worn tie rod end or other loose component on the front end, you will need get under the vehicle & have a good look & give the steering components & anything else a good shake to see if you can see anything loose or worn.........hope this helps......cheers.

Shaking of the front wheels indicates either an out of balance condition of one of the tires or a suspension component having too much play (such as ball joints). Have a front end shop check this out before a more serious condition occurs.

shake the vehicle or shake the steering wheel and listen for the noise
, let me know what youn find

Give a check on your ball joints. If you jack up the truck where the front wheels are off the ground, put your hands on either side of the tire and try to move it, if it moves up/down, your ball joints are bad, if it moves side/side, your tie rod ends are bad.

your frt brake disc rotors are warped replace them and frt brakes

you have warped frt disc rotors replace them and the brake pads!

Most common problem would be tires are out a balance. Or, the tires are out of round ( meaning the tires have a hop to it; not completely round ).

Bad universal joint