Spacer MADNESS.
 

Alright so I bought 4, 2" spacers. The 2 on the back fit very nicely (they are hub-centric) and no vibration. I installed the front ones which appear to be a nice fit and bang. The classic 40-50 mph vibration appears. Anyone know why hubcentric spacers could cause a vibrations? Studs perhaps? Or Lugs?

-2000 4x4 2dr 4.3L