The 400x and 400cx loaders came on the 4000Twenty series tractors from JD. When they switched to the R series, H180NSL (non self leveling) and H180MSL (self leveling) were the loader numbers. Same loaders, which will also fit your 4720, just different number markings. As for the Brush Hog loaders, you'll have to get on their website and check their capability chart. I'm sure they make a kit to fit your 4720.