drive shaft

[tarheelboy]

Wasn't sure where else to post this.
I have a 1989 W100, 318, auto. There is fluid leaking from the connection for the rive shaft and the rear diff. Is there a gasket that goes there that is bad maybe? Also, there is a vibration in the truck that has been there since I bought it. At 40 mph the truck bounces up and down in a perfect rhythm. Tires are new and just balanced. My manual (Haynes) mentions an out of balance drive shaft. Should there be weights visible on the drive shaft? Has anyone ever had one out of balance?

 

[88rambigblock]

sounds like you need new seals in your rear end. probably don't have your two pieces of your drive shaft clocked in the same direction. make sure your universal joints look like they are in line. if one is horizontal and the other is diagonal it will cause a severe shake. example if your front ujoint on your rar drive shaft looks like a plus sign (+) and your rear one is an x angle (x) it will be out of wack and shake you to pieces. but if you turn half of your drive shaft at the middle where it comes together and make both of them look the same your problem should be solved.