BMW Repair: vibration at high speed, guibo, cv joint

Question
Hello, I have the 2004 545 with manual trans that has the vibration between 65-70 mpph from the rear. I pulled the driveshaft and the center bearing appears ok visually, no cracks in the metal housing like you mentioned to inspect for. It does have a small amount of play like in a bad wheel bearing. The guibo has no cracks, but is pretty flexible. Fro what I recall, they are hard when new and not flexible at all. The CV joint at the rear of the driveshaft was very notchy when rotating which leads me to believe that it was possibly binding up? The car has 67,000 miles on it. What is your opinion?. I have a good ued driveshaft coming and am going to replace the guibo and trans mounts as well. thank you

Answer
Its not often I get return questions and this has been a good one.I am glad that some of what I mentioned is checked.I to,have had to start again as I thought the centerbearing metal bracket would have been cracked.As I thought about it brakes came to thought as you mentioned replacing them on your first question.My thought was a possible caliper slide or a rotor slightly warped.Things I am in hopes that are ok as you have been in that area.You mentioned the Guibo being flexible I am not sure how flexible it can be.Most times they are pretty solid.But if it was a guibo I believe you would notice it on mostly acceleration and not on a cruise.The driveshaft you mentioned getting maybe a try as it is possible that it is out of balance and that would cause a vibration a certain speeds.The mileage on the car is low in my opinion as mine all triple that if not more,but I have also replaced driveshafts on cars with less too.