Lego does not (always) track mold variants. Currently they still deliver b-type heads. Even thourgh at least for me this was very rare in 2013. As far as a I know there doesn't seem the be a system for this (or at least it isn't public - coule be possible they also have an interal number). My observation(!) was light flash variants tend to be c-types, while yellow counterparts have a higher b-type percentage. At least for me, but this may be luck. I could also confirm b/c-types are mixed in one set - even for the same print and design id. (Seen on 9471: Uruk-Hai Army)
Bricklink does track mold variants but for the heads they are not a very accurate source (they tend to use b-type even on newer sets). They don't seem to have an alternative system for the minfig (or they don't use it)
Bricklink does track mold variants but for the heads they are not a very accurate source (they tend to use b-type even on newer sets). They don't seem to have an alternative system for the minfig (or they don't use it)