My wife has a 98 4x4 Eddie Bauer Expedition and I have a few questions about it. First off, I've had a '00 Expedition that had only 4A/4HI/4LO and had nothing but problems with it jumping into 4hi while driving causing the wheel to jerk abruptly. I sold it after I failed to figure it out. We specifically bought a '98 so that we had a legitimate 2wd setting. Now, through some research, I've read that the trucks with the 2wd selection have vacuum disconnects at the hubs. Is this true? If so, when the truck is in automatic 4x4, do these hubs stay engaged or do they engage when the center diff clutch begins to lock? Hers works fine (aside from one of the speed sensors disabling A4x4, but that's no biggy). I was just curious, and having had an 07 F150 4x4, was wondering if the front end is in fact similar in this truck. Thanks

 

With a 98 there are no locking hubs, rather there is a vacuum actuator mounted on the front differential. This vacuum actuator disengages the differential ring gear when in 2H and engages it when switching to A4WD,4Hi,4Low.

 

Excellent, thanks for the clarification.