Can't really respond to developing old Kodacolor X . If you find out, spread the news, I have about 15 rolls of C-41 films to process. I can speak highly of HC-110 and 20 year old TMX (TMax 100). Processed normally at 7 min dil B at 68 degrees the results were excellent, showing no fog and just a big more grain. I have tried Rodinal on old films with pretty poor results. Good luck in your search.