Thread: 80 series landcruiser transmission cooler

Just got a reconed trans fitted and am running it on a after market trans cooler at the moment. Want to plumb in the factory cooler on the bottom of the radiator too, but want it clean as first. Any tips on flushing it out ? I have gently blown brake cleaner through it and got a lot of crap out .but seems blocked in one direction. Do they have a non return valve ? I can't see any . Just checking if any forumites may have done something similar.