Noise possibly from transfer case

[jp0863]

Only when in 4wd and going over bumps or flexing the suspension, I get a grinding noise. Does not do it in 2wd. The noise grinding noise is the same souns as tires rubbing the fender, but I know it isn't the tires. It does it fast and slow speeds. Initially I thought it was the front driveshaft rubbing on the exhaust, so I had the exhaust re-routed. The truck is high mileage, i'm guessing 195k or 295k, maybe more (shows 95k on 5 digit odometer). Anyone have this occur before?

 

[Avery4jc]

Does it sound external somewhere or like it's coming from inside the case? A high mileage 241 could easily have a chain rubbing through the lower oil pickup tube or even all the way against the case itself.