congrats on the new truck...
but...
so at the very least SHARE THE DETAILS (color, trim, options)
i had an f350 ordered but the dealer mucked the order...
so it was on to something else.
the axle/spring rating for the 05 and the '11 are identical (6100/6000)
unless either truck has some ODD combination of features or wheelbase.
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the 11 has LONGER, more progressive leaf springs at the rear, but with the same axle...
so it SHOULD (and they definitely do) ride 'softer'.
so IF the old truck/hitch combo was ok, there is NO reason to swap spring bars.
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many of the 11s are spec'd with 20 inch wheels and lower profile tires...
so THAT may affect the ride/towing some in a good or bad way.
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btw the YAW sensor that helps to 'control' the truck rear end...
most definitely will control YOUR rear end too...
cheers
2air'