I have this cooler http://www.mishimoto.co.uk/19-row-oil-cooler.html

Im struggling to find a way to pipe it in properly.

This it the original set up

http://www.realoem.com/bmw/enUS/showparts?id=CF92-EUR---E36-BMW-325tds&diagId=17_0091

There special push in connections so to adapting in a after market cooler is pretty awkward