Regarding side marker lights. I did some research and had conversations with people that remembered what happened nearly 40 years ago and here is what happened on 1968, 1969 and 1970 Chrysler product side marker lights and reflectors.
First, here is a summary of the Federal Motor Vehicle Safety Standard (FMVSS # 108) that required side marker lights OR reflectors in 1968. Notice that it specifies side marker lights AND reflectors in 1970.
Side marker lights and reflectors
In North America, amber front and red rear side marker lamps and reflectors are required. the law initially required lights or reflectors on vehicles made after 1 January 1968. This was amended to require lights and reflectors on vehicles made after 1 January 1970. These side-facing devices make the vehicles presence.
Position and direction of travel clearly visible from oblique angles. The lights are wired so as to illuminate whenever the vehicles parking and tail lamps are on, including when the headlamps are being used. Front amber side markers in North America may or may not be wired so as to flash with the turn signals.
At Chrysler Corporation we decided to do side marker lights in 1968. All vehicles except Imperial used the same side marker lights. Except for the difference in lens color they were the same lamp for the front fender and rear quarter panel. This simplification saved us a lot of money and let us do the design and engineering job a lot quicker than if we had to do unique reflectors for each carline.
During the 1968 model year we got a new Product Development (Product Planning, Styling and Engineering) Vice President by the name of Leroy Bornhouser. We called him "Bornie". Bornie took issue with the appearance of the 1968 side marker lights which he said looked liked "whales eyes". He ordered us to put side markers on the car in 1969 that were more attractive - more integrated with the sheet metal. So in 1969 we went to flush reflectors (no bulbs) that were different for each fender and quarter panel. Time was short so this took a "crash program" to meet 1969 model production.
The 1969 reflectors didn't meet 1970 standards which required lamps AND reflectors so we had to design and tool the side marker lights again. We did them three times in three years!
Thanks for asking the question. I had fun running down the details. I hope I'll be at next year's Charger get-together with my own Charger.
Regards
Burt Bouwkamp