"100% new"- - - -does that include the flex lines from the frame to the front wheels? Sometimes, the flex line on one side can collapse internally as pressure is applied, restricting pressure to one brake. The other brake applies first, pulling the truck toward that wheel. It will be more noticeable on a hard brake application, because the good brake comes on quicker. If yours is pulling to the right, check on the left brake.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!