The closed frame ones are pretty old. They almost certainly are not FMC. The open frame had two generations. The older generation had a National Audubon Society logo on the prism cover next to the right eyepiece. I'm pretty sure the older generation isn't FMC either. The newer generation has a logo on the prism near the right objective. On mine the logo says "Bausch & Lomb Birding Series". The newer generation is FMC.
If your goal is to actually use them, I would go for the newer generation open frame ones. The optics and ergonomics are excellent.