Ford's 6F35 transmission has caused me nothing but concern since I purchased this car used at 103k miles. I noticed it slipping and stuttering in the first month. The repair shop could not find anything wrong with it. Finally it died on the interstate and left my daughters stranded. This resulted in the repair shop replacing the transmission with a rebuilt one. I still have occasional stuttering and slipping after spending nearly $3200 on the repair. Not happy with the quality of this transmission. Repeated online searches shows a lot of problems with this transmission.