Some transmission questions

I have a couple questions concerning my 1999 323i,with 4 speed automatic trans.Is it possible that the trans was sourced from GM.I looked up the part number for a filter,as I would like to service the tranny.The description was 4L30E.That is very close to the GM 4L40E that was used on 99 Camaros.Both have 16 bolt pans. What fluid do most of you recommend.I guess I am more surprised that BMW was using that transmission.Thanks for any feedback