I have a ford f150 2010 platinum.

I have a vibration between 0-15 mph (Forward & Backwards) and then it goes away. It is only vibrates for 10 to 20 feet. It shakes the truck sometimes harder then other times. It feels like it is coming from the back end.
I took it into the dealer and they changed something on the transmission. this did not work.
I have a friend who has the same truck and it does not do it on his truck. It is now back at the dealer and they can drive it.

Any Ideas

 

What size bed do you have?

 

These trucks have a tendency to have the emergency brake to just barely stick on as they get older and things start to get rusty. I had it happen on my o4 STX and my 07 XLT. If this is the problem it will show up at certain speeds and then go away. On my 07 it was just a minor vib, but on the 04 it was so bad the truck felt like it was going to bouce off the road. The next time it does it lightly touch the brake and see if it changes, if so all it takes is some lubing of the parts at the rear wheels. Both of mine were still under warranty, so the dealer disassembled them lubed the parts and they were fine. Good luck and i hope it is a simple fix like mine were.