Hey guys having a longstanding problem here Had a 2" leveling kit put on back in November 12 everything seemed fine, recently had a local mechanic redo some top end seals and noticed a front differential bolt missing he put one in and since then ive began to get a howling noise from front end had it back to same mechanic he did one wheel bearing nothing changed I did the second myself still no change now since ive spent over a grand to have someone check it out for me ive started to look more myself I rotated the tires to c if possibly uneven wear while had all 4 off the ground spin the front on either side and it spins the shaft and front axle from transfer case but when I tried it out afterward in 2 wheel its still just spinning 2 wheels ( in a dirt driveway) in 4 hi it spins all 4 and 4 low seems to work fine to but I was told today from someone at ford dealer that it runs off of vacuum and in 2 wheel the front axle and both cv shafts should float because its not locked in, made sense to me. So really just need some advice on anyone having a similar problem on a 98-00 ranger or explorer 4.0 4x4. Im guessing vacuum failure or the hubs one or both are not working correctly

 

I know this is a very old post but did you ever figure it out?