Thanks for exploring this question. I'd be very interested to see some edited highlights or examples of the palindromes you did in fact reach and for which numbers, especially the biggest, and if it was anything like that figure of 9,223,372,036,854,775,807. If all the palindromes you found up to 10002 were small in comparison, then it would make 10003 sound like a promising subtractive Lychrel candidate. (I wish I knew how to do this kind of thing myself).