Planetary gear failure. It is internal from your description. Just to make sure, have your axle shafts checked for noise before considering a transmission removal and overhaul.
August, 17, 2011 AT 6:54 PM
Would it be cheaper just to buy a re-built or even new transmission?
August, 17, 2011 AT 7:27 PM
Ford reman would be about 2400 just for the trans looking at 8-10 hours labor.
A used one is a crap shoot. These trans do not have a good track record. You might get a good one or you may not. No warranty except 30 days.
August, 17, 2011 AT 11:38 PM
Could it be anything other than the transmission?
August, 17, 2011 AT 11:46 PM
Have the axles checked as I stated in the original posting.