have a 1997 F350 4x4 crewcab and intermittent growl comes in at wierd times. hit a bump and it starts and can disappear on the next bump. I cleaned and repacked front wheel bearings but did not mess with the torringtons or the Ujoints when I had it apart. mainly because I don't plan on using the 4wd until the winter but am takign the truck on a trip this summer and want to sort this out. I pulled the guts out of the LF hub and I thought that cleared it up but the next day it started again. when i pull over everythign is free spinning and can turn the outer yoke by hand. but when the noise starts it does sound like a dry torrington inside the spindle but I'm not even in 4wd. Saturday I'm goign to take the guts out of the r locking hub and see if i can make it go away. definitely feels like the L front where its coming from. I had a 1996 F250 4wd when it was new and it had the posi front/rear and I had problems with the auto hubs engaging on their own . wondering if this might be my issue? input/opinions welcome. i need this sorted out by end of june.