Bart.....there is a DOT number embossed on the lens. Google the number and it will come up with the car or truck those came off of, like a 1999 Dodge. You'll get a bunch of aftermarket responses with photos. Once you find it, look at a new one and see how it's attached.
Don & Mary
2019 Newmar Dutch Star 4018 (Freightliner)
2019 Ford Raptor