You are wrong about that. Yes,the side marker is different , but the headlight is mounted entirely diferent between 68 and 69 fenders.The 69 headlight is mounted further back as well as higher up. Comparing the two side by side it is obvious.This is why the 69 has that agressive look to the headlights,while the 68 has a somewhat bug eyed look.
It would be impossible to use the 69 grille and bezels with the 68 fenders unless you were to drill apart and weld in the front inner panels of the 69 fenders.
Good luck.I know that 69 fenders are near impossible to find from experience