[bdv1968]

Any thoughts or comments about this problem will be appreciated. I'll try and include all pertinant info. I've got an 02 f-250, 7.3, auto 4x4. The truck is lifted and runs 37's with BFG at's. With the truck in 4wd at highway speeds I'm getting a moderate roar and chatter from the front driveline, transfer case area. When I let off of the pedal it becomes a loud roar and chatter bordering on vibration. No noise at all in 2wd. Hubs locked in manual or selected auto doesn't matter. With the hubs locked in manual and the dash 4x4 selecter in 2wd I've still got the problem but I don't recall if its quite as bad. Last week I replaced both front bearing/hub assemblys with Federal Mogal units. I also did Guzzles maint and lube procedure on the stock auto/lock hubs. The axle stubs looked good with no noticable wear and ball joints were good as well. The front driveline universals seem to be good but I wonder if it would be a different story if I pulled the shaft and checked them again. I'm leaning towards this shaft or the output bearing of the transfer case. Has anyone heard of this before?