My Great Grandfather was in the 66th co D, I also have found little on the 66th, The most information I found was the book Four Years on The Fireing Line, by Col Nesbitt, this book starts at the beginning of the Atlanta campain in Chattonooga but ends when Nesbitt is taken prisioner in Atlanta, The 66th fought at Nashville then retreated into Alabama and later boarded trains and went to North Carolina and fought at Bentonville where they surrendered with Johnson, If you find any information I would like to hear from you.