I have the same vibration in the steering wheel. For me its between 60-70mph. Not sure what it is. Going to get it aligned and new tires here in a few weeks. In the past, I had it aligned and it didn't help, replaced worn cv's and it didn't help either. Only thing that really made a difference was the new double cardan driveshaft.
99' WJ 4.7, 3.5" lift, Bilsteins, JKS goodies, 32" Guard Dogs on 16x7 4" BS Soft 8s