Fram quick change oil drain plug

Hello... I am looking to put one of the new Fram "SureDrain" oil plug in the bottom of my 97 C230. I don't think that Fram has one for my car, yet, but I would consider having an adapter machined. Any ideas of the thread spec on the MB C230 drain plug? Short of me pulling mine out and taking it to a hardware store, I am at a loss of how to find this out. The block is aluminum, so I was going to have an adapter machined out of aluminum as well.

Thanks,
Doug. :idea: