support for the 2 piece drive shaft. Get it up on a rack and inspect. As far as a 1 piece driveshaft they are sometimes difficult to dial in to be free of vibrations and weird harmonics. I tried one once and gave up. Carefully inspect the 2 piece but with 250k miles I suspect the driveshaft needs repair for the center surpport bearing and if any of the the 4 universal joints are bad they cannot be replaced.