On the Tao Te Ching
One excellent version of the Tao Te Ching that I have, translated by Red Pine, uses heng2 (恆, U+6046) in the place of where practically all the online texts use chang2 (常, U+5E38), without a precise explanation why. I suspect that it may be based on the Mawangtui or some other early text. The introduction of the book alone shows the meticulous work that the author has put into researching and translating it, so whatever the reason behind the difference, it must be quite compelling. Here's the original text used for his English translation of the first verse:
In its article on the Tao Te Ching, Wikipedia mentions the 1993 discovery of the Guodian Laozi, the oldest version of the Tao Te Ching yet found, dating from about 300 BC. The article also states that "this find unearthed 14 verses previously unknown". The only possible extra verse that I've been able to find, however, is the Taiyi Sheng Shui, and it's not even known whether this was intended to be an extra verse of the Tao Te Ching or not. I've also been unable to find an English translation, though the Chinese University of Hong Kong has a site which reputedly contains the Chinese original.
Cite: Palmer, S.B. (2005). "On the Tao Te Ching", in: What Planet is This?
Archival URI: http://inamidst.com/notes/onthettc