'04 F-150 automatic tranny. Cruising along I-10 at about 60-65 and decided to pass someone. Mashed the gas and it downshifted. When it attempted to upshift again... nothing. RPMs go up and truck just coasts. This happened suddenly. I haven't been noticing any gradual slipping or anything recently. Just bam and no 4th gear. I can turn off the O/D and it runs along fine although with much worse gas mileage. Do I need a rebuild? Would I be better off getting a salvage yard tranny? Any advice is appreciated.