The existing lights, if like you say, are 2 foot square boxes with a hinged plastic lense, they mount to the deck with either bolts and nuts or if newer with 4 tech screws. The deck that you see is in most cases the roof. Mobil uses some double deck jobs which are a real pain to work on
Don't see how you can bid a retrofit without knowing what is going back up. If indeed they are Scottsdales they require some patience and some labor to install.
Scottsdale actually makes a kit to fit in existing boxes, save some time and money, not sure they look as good though?
