The latest volume includes details of fragments showing third- and fourth-century versions of the Book of Revelations. Intriguingly, the number assigned to "the Beast" of Revelations isn't the usual 666, but 616.and Ed comments:
My copy of Nestle-Aland (27th ed.) at Revelation 13:18 lists for the variant reading "616" only "C; Ir mss" (the 5th century uncial manuscript C and some manuscripts cited by Irenaeus). A 3rd or 4th century papyrus containing this reading would be extremely significant, although probably not enough to outweigh the many witnesses for "666."The relevant article here is the following:
David C. Parker, "A New Oxyrhynchus Papyrus of Revelation: P115 (P.Oxy 4499)", NTS 46 (2000): 159-74
There is a very brief discussion of the variant in question on 169.