I took my truck in 3 times for the shuddering at 80km/hr and shifting problems to the Ford Dealer here without them being able to duplicate the problem. Last week finally got some time to take the manager for a test drive and oooh they finally noticed it.
Ended up being that the rear drive shaft was out of alignment and my PCM needed to be flashed and reprogrammed. So far the truck is running great and already noticed better fuel mileage off since. The shifting is great and no more shuddering...

 

Split driveshaft???

 

Im pretty sure the 6.5ft beds come with a split drive shaft.

 

curious as to what and how the fix was done for the alignment of the driveshaft.....

 

Mine is one piece.

 

mine is the 6.5 ft box... the techs here said they got a new piece of equipment to detect where the vibrations come from, so they hooked that up, test drove it and determined it was in the rear and aligned it...no idea how they aligned it, but theres no more vibrations...

 

alot more happy now with the truck... before this every drive was like you were strapped in a chair and drank way to much strong coffee...your knees were just vibrating at any time you got between 70-80km

 

Was this a SCREW w/ 6.5' box/ 157" WB?

 

Yup 2011 lariat EB screw 6.5' box with 3.73 gears, 20" rims, max tow package and the shuddering problem came right when i got it in june but the techs said they couldnt duplicate the problem...it was mainly felt when we were towing or hauling the quad in the back but then got worse till you could feel it whenever you got up to speed