If it is running alright I would leave it alone - or better yet ride by Benzmac place of work and get him to check it for you. It is my opinion that getting the tranny fluid right is one of the hardest things to do on MB cars. Anyway to answer your question the tranny dipstick should be on the passenger side against the engine close to the firewall. Look for the red cap. Keep in mind, and I do not know if yours is applicable or not, but some of them do not have a dipstick on the tranny.