for some reason my dads 97 F350XL crewcab is shift really hard and at wierd RPMS than usual, also the overdrive light flashs and the speedo stops working at the same time. I've replaced the speed sensor on the rear axle and then the throttle position sensor, and I've replaced every single fuse in the truck. if you have a solution or a idea let me know. thanks

 

You might look on the side of the tranny where the shift linkage goes into it, there is an electronic part there that helps control the shifting, and it is adjustable. It is an easy fix if its the problem, if not there is another electronic part inside the pan that could be bad also. Im not a tranny guy, I have a buddy that had that same problem a month ago and fixed it by replacing the part on the shift linkage.

Hope this helps