My 97 f150 4x4 with 120,000miles has a shake/shudder when driving at speeds around 60mph. I think it is coming from the driveshaft, because the problem doesn't seem to come from the steering wheel. Will this vibration cause other problems later with the truck if I contine driving it with it shaking the truck? If so, should I replace the driveshaft, or do something else? Any help is appreciated!

 

Check the u joints. If they have not been changed then they are WAAAAY over due. Give that a look. Yes, it will cause other problems. For example the pinion bearings and seals or the tranny seals will start leaking.