Bilstein has adjustable front struts for 3rd gens as well. 06+ 1500 4wd's use a strut suspension. The Bilsteins just offer one notch less lift height than the 4th gens. As the OP stated, he's has them set at max which is 2" on a 3rd gen.Ok. I think I understand now. You got the 5100' but they provide no lift since it's an 08. You are asking if it is ok to use spacers with those shocks. The answer is yes. I think both Brandon and I were thinking the were the leveling 5100's. My bad. If you want to level it is your only coice to use spacers since the Bilsteins won't level for you. Put a little more info on your truck in your sig and it will help others know what you need.