HELP - Steering rattles and creaks when warmed up

[2010F350Dually]

Brand new 2010 F350 dually FX4 has a steering problem when the truck has been run long enough for the engine bay to get fully warmed up. The steering creaks and there is a rattle in the column while operating on the freeway or over bumps. Feels loose somewhere, but everything is tight as far as I can tell. When the truck is cold, all is well. When I drive on freeway for 10 miles, I start getting a creaking/rattling noise and feel it in the steering wheel. If I tap my brakes, I feel it, go over speed hump...can hear a creak and feel it. What's up??? Anyone? Problem I have is that dealer will do a drive after it sits for a while and they will never find the problem.

[2010F350Dually]

Had lower steering column replaced under warranty for the rattle and creaking it would exhibit while engine bay was hot. Never happened when cold. The steering column is splined together and the rattle/creak caused by imperfect marriage of the 2...all is well now.

** Surprised nobody replied or had any similar experience???