Another bent driveshaft thread

Not only have I heard of this, but I am experiencing it. I had a local shop build it. Proven Force, or as they used to be called, Clutch and U-Joint have made shafts for me in the past. I have been fighting a vibration since I put the motor and tranny in a year and a half ago. I took the driveshaft out and had PF check the balance. I took it to a different place to check the balance just to get different eyes on it. The other place didn't give me a lot of confidence, and then they counter balanced the weights. I put it on the hoist a couple of weeks ago and there was little movement at the yokes, but the center of the shaft had 1/4" to 3/8" runout. It was bent. I sent it in today. They verified the bend but were concerned on the length. The slip yoke rides well back and I was always afraid it was too short. I wanted it back so I could drive tomorrow, but they cut the yoke off so I can slide it in and remeasure to make sure I get the right length. I can wait a day if it gets rid of this damn vibration. Just a little off at high speeds can make a huge difference. My tires turn 780 revolutions per mile at 45 mph. if my math is correct, my shaft should spin 3198? How much more at 100 or 120 mph?