cant figure out the squeak
 

my 02 duramax w/ 6" lift on 35s started squeaking the other day when i got on the pedal real hard. now it only does it after the truck has warmed up and is especially worse going up and down my gravel driveway. i replaced alot of parts on my front end and now noticed the only time it goes away is when i hold the break down. a mechanic told me its in my brakes but the pads are brand new. he also said my hydrobooster was leaking. im not sure about that one. but this problem has stumped me any help on getting rid of this embarassing loud squeak would be greatly appreciated thanks

Squeek or squeel?

sqeak i think im not sure but it gets worse when i turn to the right.

Sounds like a bearing or suspension problem. The right side bearings go out in everything premature because that is on the down hill side of the road, more weight transfer, that is also the lower portion of the road so the water does damage to the road, beats up the right side suspension, thats your blind side, hitting the curb or pot holes.

well earlier today i noticed my brake pedal shaking a little and when i looked at it from inside the cab under the dash there is a rod that comes off the brake and goes into the firewall. where it goes in the fire wall it conects into a cylinder looking object and its leaking from that cylinder. so whenever it started squeeking going down the road i put my foot UNDER the brake and pulled up twards me so it couldnt shake anymore and the squeek went away. what is that cylinder thing and what part should i change any ideas??

That cylinder is your hydroboost. So your mechanic was right if you see a leak. You need to get that fixed imediately.

Wheel bearings. Mine did a similar thing. Easy to check and replace