I can tell you from personal experience....there is NO WAY in hell that you can properly install a '96-'98 OEM rear lip without taking the bumper off. If you want to do it half a$$ed, then maybe...but if you do it the right way, you have to take the bumper off. The '99-'00 one is about 5000x easier, and you do not have to remove the bumper to do it....it installs the same way that a '96-'98 Front lip does with clip nuts and bolts. Aftermarket lips may be a totally different story, and I can't attest to this b/c I went with the OEM route. I hope this clears up any confusion.