I have several 1968 Skylarks. They all have a round rear side marker lenses that are hard to find and usually pricey. I thought I'd share a picture of some I/we made. An employee and I made some silicone molds from an intact lens and insert. We used resin in the molds in a pressure pot to form the reproductions. We had to polish the clear cover with fine grit abrasive to get the clear effect.