What episodes in the anime, Detective Conan, does Conan turn back into Shinichi Kudo?

I am on episode 129 in the JAPANESE VERSION, and I was wondering what episodes does he turn back into Kudo. I know he doesn't stay, but I just need to know. Also does Ran ever find out? I know she gets close but Conan always deters her. Please just let me know. I don't want to go to a link. Is this not the longest running anime? Is it soon going to be over?