RepairPal Certified shops can diagnose and repair your 2003 Buick LeSabre. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
You will find complete Headlamp Horizontal & Vertical Aiming in the Owner's Manual (Section 5-51).
You can get the vehicle's Owners Manual here; http://repairpal.com/automobile-owners-manuals-online