Drivetrain WHine 1500 RAM Big Horn

[Oly]

It appears that I am one of the many with this problem. I experience a drive train whine which at times is so loud that I would call it a howl. This noise happens under very specific circumstances. It only happens between 1450 & 1550 rpm regardless of what gear it is in, and is loudest at 1500 rpm. Also if I hold the engine at 1500 rpms the noise fades in and out at 10 second intervals. Here is the curve ball. It only does this when I am pulling an 1800 pound pop up camper. This only happens while pulling this trailer. I have pulled a 1200 pound cargo trailer, and a 4000 pound stock trailer with absolutely no problem. Since it is engine rpm and towing related I figure this problem lies somewhere between the flywheel, and the first U-joint. Here comes the fun part. I have made 2 appointments for warranty repairs. However since it is not making the noise when I bring it in for their ears of Mozart mechanic to listen to they refuse to look at it. Here comes even more fun. I have made 3 trips with this camper, and this problem only occurred on 2 out of the 3 trips. One trip it happened for the 250 miles down, and the 250 miles back, but not while the camper was disconnected at the site in between. The second trip it was trouble free the whole way. The third trip was 300 miles down and back with the noise being there the whole way, and briefly for one 20 mile trip with the trailer disconnected. Any suggestions as to the nature of this problem, or who I might contact at Dodge/Ram/Fiat that might have an answer?