My 2010 Lariet 4X4 Screw has 48,000 trouble free miles on it. For the last week or two I have noticed that the transmission is acting a little strange. Under light load and going maybe 30 miles per hour I am experiencing rough shifts. Up and down shifts are much firmer than they have been in the past. I hear a thunk sound when this happens.

Any opinions as to what is going on? I have an extended warranty through Ford so I can go to the dealer. Just want to be armed with as much info as possible before I take it in.

Matt