I am not sure what kind of weight bracket JD has for their 4000 series. I have a JD 5300 and the Kubota weights are greatly different. The kubota weights have a fairly long "tongue" on the front which I believe probably makes them fairly specific for a Kubota bracket. I also got the dealer to throw in a second weight bracket for free. (Most kubota's he sells have FEL. For the FEL to attach the weight bracket is removed and the loader mounting bracket is added. I bet he had 20-30 of these brackets.) The weights I bought were a little scratched and had slight surface rust. He also rents tractors and maybe he had used them before. I bought a can of Kubota gray paint, sprayed them, and now they look new. I modifed one bracket and mounted it on a 4"X6" angle iron. This goes over the existing FEL bracket and I use the removable loader pins to attach the angle iron. Quick on and off. (The loader has to be off to use the weight bracket) I use the 2nd bracket mounted to a 3pt. tow bracket. The 2nd bracket and weights can then be used as rear end ballast.