You can put the 2dr bumper on your 4dr with little or no modification, but it wont fit too good since the fenders are different. The only way to make it fit right is to make your own fenders. To do it you need to cut your 4dr fender and weld the front part of a 2dr fender, looks really good if its done right. Attached is a pic of one that had this done. I plan to do the same eventually.