I dont think the carnifex ever got an update after the plastic kit that came out in 4th edition.
Each fex came with I think 6 head variants (with 2 of the heads, the damaged "old one eye" one and the normal head sharing the left side). This included the Bio-plasma, Enhanced Senses, Acid Tongue and Tusks (which were all upgrades at one point, but are now just for decoration).
As for weapons, it came with a pair of Devourers, a pair of Deathspitters, one Heavy Venom Cannon, one Stranglethorn cannon, one pair of Crushing Claws, and two pairs of Scything Talons. One set of Scything Talons came on the carnifex sprues themselves, another set came on the "Monstrous bioweapons" sprue that the carnifex, at the time, shared with the metal Hive Tyrant. It also came with three types of carapace, use to represent spinebanks and spore cysts before.
Here's a good pic of the sprues:
http://www.librarium-online.com/wp-content/uploads/2008/10/7180217.jpg