Hamb cl***ifieds, eBay or local online sales. A few places repo the 682-C but not sure on just the upper light housing.
I'd look at finding an original housing; while an OTB gear part can be worked to fit, it is not the same. If you want good chrome rings; you can't go wrong with their rings, perfect fit and look great.
So there are two versions of the parking light retainer and at least two different lens shapes for originals. I saw a pair of the bigger window retainers on Irontrapfinds instagram page just yesterday, $70 for the pair I think, and the post was way down the list.
Here is a link to some Guide history from a previous thread on 682's, and from which I borrowed the photo that I posted above. http://www.hotroddisorder.com/2013/01/guide-to-blc-headlights.html
https://irontrapgarage.com/ Because the hamb is a hot spot for guys staying off social media here is iron traps webpage which does have the entire listed inventory of the shop and is searchable. they have an obscene back inventory as well so if it’s not listed you can reach out to them about a part. The email listed on the email is the preferred form of contact.