It's worth noting that 1000 series does not necessarily come with diodes. Some do, some don't. There isn't a sure way of knowing with standard "1000"s, however there are some models that ALWAYS have them such as the G80-1191, G80-1207 and G80-1501.
I am also cautious to lump all "vintage" blacks together. I have NIB Cherry G80 keyboards from pre-1988, 1988, 1990, and many other years all with MX blacks, and even between those there is a difference in smoothness and feel.