I need to replace one of mine and whilst I appreciate its a bumper off job, what else is entailed re then light unit?. Is it a case of just unscrew the existing one and screw in the new one? Do is it need to be coded or aligned ?. I'd have thought it wouldnt of needed aligning as they are self levelling and screw into the same place as the old one. I'm thinking of doing this job myself if the dealers price is too expensive and whilst there replacing the front grille with the black optics one. Any help appreciated.