Hot ATF after trailer rides

Who can tell me if I can build the Gertiebeölkühler from 4.2 Gertiebe on mine from 3.6 Bj.90? If this has worked out, a set of these are located (cooler, lines ect. ???). Or do I have to use a grate of 4.2??
Who can help me in this, I am grateful for every answer !!

Mfg Bjorn