If the steering wheel is shaking it is almost always going to be the front end. If you get a shaking throughout the truck and in your seat itll almost always be the rear. I did the 2.5'' level on mine a few weeks ago and forgot to tighten a sway bay all the way and got a death wobble at about 40mph. That then led me to notice all my tie rods and left hub needed changed as well. If you do happen to replace tie rods (tightened up my front end tremendously) make sure to spend the few extra dollars and go with "Moog", they'll last a long time and have lifetime warranty. O'Reillys will have them in stock. If youre half way mechanically inclined, do it yourself. Took me about an hour and a half and cost $315 from O'Reillys and the local shop wanted $652 to put them all on. OUTRAGEOUS. local chain stores were $550+ Im glad I did it myself, wasnt hard at all.
Im with these guys though, although you should check your tie rods, sway bar and shake the wheel for any play in your hub... start at the rotors. Simple to replace and if you stood on them a couple times or got them hot after the Stealership turned them for you (making them thinner) they could have easily warped being that theyre not as thick now.