Michael,
Concerning Codex C:
EPHRAEMI RESCRIPTUS (C), [located in] BIBLOTHEQUE NATIONALE IN PARIS. One of the old uncials.
Written originally in the 5th century and containing the whole of both Testaments it was in the 12th century converted into a palimpsest. That is, the original writing was washed out, and some works of a certain Ephraim Syrus were written over it. Many leaves also were thrown away. It now contains parts of all the NT books except for II Thessalonians and II John. Much of the original writing has been discerned. (Kenyon). Strouse says the text is mixed but pro-Byzantine. Kenyon (as we would expect) speaks of this Byzantine presence being due to "its correctors."
Burgon would rank this codex behind Alexandrinus as having the fewer corruptions among the "five old uncials".
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I got this info from the online version of
Forever Settled, Part Four : A Survey of New Testament Documents, by Jack Moorman. A sound and informative book.
Hope this helps.