Contacting people, and rebuilt cars

I've got a couple of questions that I'm sure you guys can answer. First, does someone have Robert Sloans E-mail address, if he has one, or some way for me to contact him? I just got a copy of his latest book, a century+ten of NG freight cars, and it's incredible! If anyone wants to learn a lot more about the Rio Grandes feight cars, you've got to have this book.
Second, when John Templeton put up the information about the 6300 series flats, it sparked my interest to see if there are other rebuilt cars. I know that the 6700 flats were made from boxcars, and Bob Sloan said that only the first 25 cars are from know numbers. What I am curious about is if there were other NG cars made from other NG cars, and what were their numbers originally.
Any information would be greatly appreciated.