Re: Bilstein Strut install, no bumper.
If you're referring to the bump stops, then yes you do need them. There are no bump stops to replace in the rear unless you changed coil springs. The front struts will need to be completely removed again, coil springs compressed, and top mounting plates removed in order to install the bump stops if you didn't install them originally. There is no need to be cutting any shafts.
You should have received new bump stops with the front struts. Otherwise, you have to reuse the old ones. Without the bump stops the first hole you run over will either A. Knock a few teeth loose and/or B. Completely destroy the strut.
2006 Jeep Grand Cherokee Overland 5.7L, BT Catch Can, SRT Eibach Pro Kit, 20" SRT Factory Repros, SRT Front and Rear Bumper and Side Skirts, LED interior lighting, SRT aluminum interior trim, SRT steering wheel, Shorty Billet Antenna, SRT intake, SRT exhaust with 4" double wall tips.