Trying to restore my late mamas 04 Silverado Regency Sport that my ex intentionally destroyed. I need to know which years will interchange. I need basically the entire front clip; grill, hood, fenders, core support, condensor coil, air filter box, headlights, tailgate and possibly heater motor

 

07 was a change year for the Silverado. The early 07 looked like like your 04 and the later 07 was a new body style. So the early 07 parts will fit although the grille and some other parts may be different.