I think I might have a serious problem with my front diff, when I'm in 4wheel drive I get a bad vibration-rumbling sound (not really grinding), it goes away in 2hi, I just had the IWE solenoid replaced last week and both actuators, the hubs are fine also, and cv's are good to. I have no idea what the hell is goin on! I have a 2005 fx4 f150 6in fabtech lift with coilovers and 35in tires