I have a '68 122 that I want to sell. I recently listed it on e-bay and the item sold. The high bidder came to get the car and took it on a test drive. He came back saying he thought the rear end is bad and that he could not complete the sale. I don't want to force anyone to buy the car who doesn't want to, but now I am concerned about the rear end issue. I took the car for a drive and there is a noise coming from underneath. It happens under power when going straight or turning. It is a pulsating noise that increases with speed. How can I determine if the problem is a bad rear end? If the rear end is no good what is the best (most economical) way of fixing it. I have extended an offer to the next-highest bidder to buy the car, but don't want to misrepresent its condition.