Having worked at dealerships through the '70's, I remember a lot of vendors would drop by and try to sell different modification packages. The custom van companies were the worst and would try and do different modifications to help the dealer make more 'profit'.
The vinyl roof trim, bodyside mouldings and door edge guards were examples of this. Portholes really became popular in the 70's into the 80's. And later on they were usually accompanied with the padded vinyl roofs. Add-on air, radio/stereo packages, cb- radios and car alarms were added too. Of course there were aftermarket bumpers and tire/wheel combinations that were done as well.
And I almost forgot about undercoating!
The idea that the add-ons were actually installed by the dealer is very incorrect. Usually the work was completed at a local bodyshop, upholstery shop or electronics vendor.
Anyone remember the 'protectant sealer packages' the dealers would have applied to the paint and upholstery? Some dealers added $1000. or more to the sticker just for this junk!
Ray