I'm betting it would be cheaper and easier in the long run to just slap a new radiator in it every 30 years. Also, the trans cooler does double duty, it not only cools the trans, but being a water/oil exchanger, it also helps to keep the trans at the proper temp in cold weather. Unless you are pulling a heavy trailer or hauling moonshine up the mountainside (and everybody knows you haul moonshine DOWN the mountain), there is no call for an additional cooler. The weak Mercedes trans will give it up before it overheats.