High Speed Vibration/noise
 

I have a 61 220SE, with rebuit engine, fuel system, the works. In addition, I changed the real axle out from the 4:10 to 3:23. I have also done some clutch work. The body is at best, fair (so it is a little lose). The car runs wonderful in any conditions but....... In fourth gear above 2500 rpm the car vibrats a lot and is much louder but ONLY WHEN YOUR FOOT IS ON THE GAS. Above 3200 rmp, I still have some vibration but not as much. Below 2300 rpm no vibration what so ever. When the car is cold there is little or no vibration at any speed. After about 20 min at high speed the vibration starts. Does anyone have any idea where I shoud start looking to cure this problem?

Thanks,
Michael

vibration
 

I would have to suggest checking the drive shaft. I'm not sure about a 40 year old car if it has a center ujoint or not.:confused: