A rear-mounted radiator makes for a cleaner engine bay, and distributes weight to the rear for better balance. Those are the advantages. As with everything else, there's no such thing as a free lunch. It takes a lot of plumbing to get the coolant all the way to the rear of the truck and back up to the front. The second difficulty is that the radiator is not in the best position for catching enough cooling air, even with the wing on the back to help direct airflow. This setup has worked acceptably, but not well enough to inspire confidence to run long races in triple-digit desert heat. There's a PWR radiator and a pair of Spal fans sitting in the shop, waiting to be installed in the cab's rear window.