They're getting harder to find, and there are a lot of Macs with that interface. Even some ethernet cards. Apple made an LC ethernet card which only has the AAUI interface. I think the entire NuBus PowerMac family has AAUI only. And, IIRC, the first PCI PowerMacs has the AAUI, but they also have an RJ-45 jack, so it would be kind of pointless to use the adapter on those. Did some of the Quadras use it as well?