Try these two companies.
Mr. G probably has them. You'll have to look through his extensive catalog online or call him. I've gotten a lot of obscure stuff from him.
Mr. G’s Enterprises Automotive fasteners, of all types
5613 Elliot Reeder Road
Fort Worth, Texas 76117-6013
817-831-3501 or 817-838-3131
https://mrgusa.com/fasteners/Fastener Connection Weatherstrip, fender welt, fasteners, clips, fittings, trim retainers, rivets, bulbs
http://www.thefastenerconnection.com/index.html