68 saw a lot of federally mandated changes including
" reflection" or glare.
The rear view mirror was black and no longer chrome due to glare to oncoming traffic. Plus its stalk painted satin silver not chrome
Ditto first year for satin finished wiper blades and arms.
No more shiny " wings" on the blades.
Interior window garnish trim no longer chrome.
Front turn signals had to be amber lenses and as mentioned had to be bigger.
Comparing my 67 Monaco to my 68 Newport these are the most obvious differences.