I took my truck into the dealer about 4 months ago with a droning noise between 95 and 100k.The dealer replaced the drivetrain from the transfer case back to the rearend.This did not fix the problem but i lived with it because i got busy and was't towing or hauling at the time.Well better weather is coming so i took it back in and the dealer kept the truck for a couple of days.They reset the exhaust system and moved the oil stick or tranny dipstick and the drone went away.Man i'm happy as that drone was really irratating under load hope this helps someone cheers....

 

More info please?