They do go into the radiator. That is the stock tranny cooler. It cools the fluid to 195 degrees. The aftermarket cooler should be run after the fluid leaves the radiator, but before it returns to the tranny. Your looking for a final inpan fluid temp, after both coolers, to be around 125 degrees I believe. I dont know which line is the return and which is the feed though, have to get someone else for that.